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Turning forces & shapes

Date:

Time: Total marks available: Total marks achieved: ______

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Questions

Q1.A student uses this apparatus to investigate how the strength of the magnetic field in a current-carrying coil varies as the current changes.

This is the student's method. attach a small magnet to one end of a wooden rod place the rod on a pivot that is 8 cm from the magnet attach a weight holder to the other end of the rod place a current-carrying coil underneath the magnet

(a) A weight of 0.1 N is needed to balance the rod when the current in the coil is zero.

Calculate the weight of the magnet. [ignore weight of rod and weight holder]

(3)

weight of magnet = ........................................................... N

(b) The student increases the current and observes that the rod rotates anticlockwise and the magnet moves towards the coil.

Explain this observation.(3)

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(c) The student adds weights to balance the rod for different currents.

The table shows her results.

(i) Plot a graph of the student's results, with the independent variable on the x-axis.(4)

(ii) Draw a straight line of best fit.(1)

(iii) Suggest why the student should repeat the reading for a current of 0.7 A.

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(2) .............................................................................................................................................

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(iv) Describe the relationship between the current and the force produced by the magnetic field.(2)

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(v) Estimate the weight needed to balance the rod when the current is 2 A.(2)

weight needed = ........................................................... N

(Total for question = 17 marks) Q2.A toy train is placed on the middle of a bridge on a model railway. force

The weight of the train acts through its centre of gravity.

Ignore the weight of the bridge.

(a) Which row of the table shows the correct values for forces X and Y?

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(b) Describe how force X changes if the train moves from P to Q.

(2).............................................................................................................................................

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(Total for question = 3 marks) Q3.A man uses a wheelbarrow to carry some logs along a flat path, as shown.

(a) He pushes with a horizontal force of 140N and the wheelbarrow moves 39m.

(i) State the relationship between work done, force and distance moved.(1)

(ii) Calculate the work done moving the wheelbarrow.(2)

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work done = ........................................................... J

(iii) State how much energy is transferred to the wheelbarrow.(1)

energy transferred = ........................................................... J

b) The man stops and holds the wheelbarrow horizontally, as shown.

The man exerts a total upward force of F N.

The weight of the loaded wheelbarrow is 470N.(i) Mark on the diagram to indicate the centre of gravity of the loaded wheelbarrow.

(1)

(ii) State the equation linking moment, force and perpendicular distance from the pivot.(1)

(iii) Calculate the force F.(4)

force F = ........................................................... N

(Total for question = 10 marks) Q4.(a) A man stands on a wooden board to paint a wall, as shown in diagram 1.

The diagram shows some of the forces acting.

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(i) State the principle of moments.(1)

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(ii) Calculate force X.[ignore the weight of the wooden board]

(4)

force X ............................................................. N

(b) The man walks to the other end of the wooden board, as shown in diagram 2.

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Explain the change in force X as the man walks along the wooden board.(3)

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(Total for question = 8 marks) Q5.(a) The diagram shows how a mechanic applies a force on a spanner to try to undo a bolt.

(i) State the equation linking moment, force and perpendicular distance from the pivot.(1)

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(ii) Calculate the force required to produce a moment of 4.8 N m.(4)

force = ........................................................... N

(b) The mechanic is not able to undo the bolt because a moment of 9.6 N m is needed.

Explain how the mechanic could produce a moment of 9.6 N m.(2)

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(Total for question = 7 marks) Q6.A student investigates the extension of an elastic band for different forces.

(a) (i) List the laboratory apparatus that the student needs for this investigation.

(3).............................................................................................................................................

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(ii) Extension, force and temperature are variables for this investigation.Draw a line from each variable to its type.

(2)

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(iii) Describe how the student can measure the extension of the elastic band when he adds a force of 12 N.

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(b) The student obtains this data as he first adds weights to the elastic band (loading) and as he then removes weights from the band (unloading).

He plots the loading data on a graph as shown.(i) Suggest how the student could improve the quality of his data.

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(ii) Draw a curve of best fit through the loading data. of 56

(1)(iii) On the same axes, plot the unloading data.

(2)(iv) Draw a curve of best fit through the unloading data.

(1)(v) The student concludes that the band is an elastic material and that it obeys Hooke's law.

Discuss whether his conclusion is correct.You should support your argument with data.

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(Total for question = 16 marks) Q7.A student investigates whether a spring obeys Hooke's law.

She uses the apparatus shown in the photograph.

(a) Which additional measuring instrument does the student need for the investigation?

(1) .............................................................................................................................................

(b) Explain how the student can investigate whether the spring obeys Hooke's law.

(5)

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(Total for question = 6 marks)Q8.A person has a suitcase with wheels.

(a) The person pulls the suitcase with a horizontal force of 13 N for 110 m.

(i) State the equation linking work done, force and distance moved.(1)

(ii) Calculate the work done on the suitcase by the person.(2)

work done = ...........................................................J

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(iii) How much energy is transferred to the suitcase?(1)

energy transferred = ...........................................................J

(b) The suitcase falls over.

Explain why it loses gravitational potential energy when it falls.(2)

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(c) The person starts to raise the suitcase again by pulling on the handle with force F.

The weight of the suitcase is 150 N.

(i) State the equation linking moment, force and perpendicular distance from the pivot.

(1) .............................................................................................................................................

(ii) Calculate the force F that the person must apply on the handle to start raising the suitcase.

(3)

force F = ...........................................................N

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(Total for question = 10 marks)

Q9.A student investigates how the extension of a spring varies when he hangs different loads from it.

(a) Write a plan for the student's investigation.

Your plan should include details of how the student can make accurate measurements.

You may add to the diagram to help your answer.(5)

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(b) The student finds that the spring obeys Hooke's law.

Draw a graph on the axes to show the Hooke's law relationship.

Label the axes.(3)

(c) The student concludes that the spring shows elastic behaviour.

Explain what is meant by the term elastic behaviour.(2)

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(Total for Question = 10 marks)

Q10.The diagram shows an air track that can be used to investigate motion.

Air comes out through a series of small holes in the air track.

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A small glider floats on a cushion of air.

(a) (i) The diagram below shows the glider at rest on the air track.

Complete the diagram to show the forces acting on the glider.Label the forces.One force arrow has been drawn for you.

(3)

(ii) Explain what effect the cushion of air has on the movement of the glider.(2)

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(b) Two light gates connected to a data logger are placed above the air track so that the card will pass through them.

The glider moves at a constant speed to the right.

The length of the card is 8.3 cm.The card takes 314 ms to pass through the first light gate.

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(i) State the relationship between average speed, distance moved and time taken.(1)

(ii) Calculate the average speed of the card as it passes through the first light gate.(2)

average speed = .................................................. cm/s

(iii) State the time taken for the card to pass through the second light gate.(1)

time taken = .................................................. ms

(Total for question = 9 marks)Q11.A student investigates friction between a block of wood and different types of surface.

(a) The student uses the equipment shown in photograph A to measure the force needed to move the block of wood.

(i) Suggest why the student places masses on the block.(1)

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(ii) Explain why he keeps the masses constant during the experiment.(1)

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(b) The student investigates five different types of surface.The table shows his results.

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(i) Give an example of a non-continuous variable in this investigation.(1)

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(ii) Complete the table by inserting the missing average.(1)

(iii) Display the average force results for this investigation on the grid.(4)

(c) The student compares his results with others in the class.He finds that they have different values for the forces.Suggest why.

(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................

(d) The student repeats the investigation using another block of wood as shown in photograph B.

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This block of wood has the same mass but a different area of contact.Explain how this change affects the pressure on the surface.

(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................

(e) Suggest two ways in which the student could reduce friction between the two surfaces.(2)

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(Total for question = 14 marks)Q12.The photograph shows a child bouncing on a trampoline.

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(a) The box lists some types of energy.

The passage describes the process of bouncing on the trampoline.Use words from the box to complete the passage.Each word may be used once, more than once or not at all.

(4)As the child falls, his ............................................................................................. energyis mostly transferred to ............................................................................................. energy.When the child hits the trampoline, his ............................................................................................. energyis transferred to ............................................................................................. energy.

(b) Trampolines have springs that stretch and compress.

A student investigates a spring to see if it obeys Hooke's law.She measures the extension of a spring for a range of different stretching forces.(i) Describe how the student could measure the extension of the spring.

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(ii) The student finds that the spring does obey Hooke's law.Sketch a graph of her results on the axes.

(2)

(Total for question = 9 marks) Q13.The diagram shows the apparatus used to investigate moments.

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The 2 N weight is placed 60 cm from the pivot.

The newtonmeter is placed 10 cm from the pivot.

(a) (i) State the equation linking moment, force and perpendicular distance from the pivot.

(1)

(ii) Calculate the reading on the newtonmeter.Ignore the weight of the ruler.

(3)

reading = ............................................... N

(b) The metre rule is replaced by an iron bar.

The iron bar is 1 m long and has a weight of 10 N.The newtonmeter and the 2 N weight stay in their original position.Explain how this change affects the reading on the newtonmeter.

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(Total for question = 7 marks) Q14.A student investigates the motion of a 10 cm square piece of card as it falls.

He attaches some weights to the bottom of the card to make sure it falls vertically.

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(a) Add an X to the diagram to show the position of the centre of gravity after the weights have been attached.

(1)(b) The student writes this plan for his investigation.

Which of these is the dependent variable in the student's investigation?(1)

A the final speed of the card B the initial height of the card C the initial speed of the card D the mass of the card

(c) The table shows the student's results.

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(i) Complete the table by calculating the missing average.Give your answer to two decimal places.

(2)(ii) Plot a graph to show how the average final speed changes with height.

(4)

(iii) Circle the anomalous point on the graph.(1)

(iv) Add a curve of best fit to the graph.(1)

(v) Describe the relationship between height and average final speed.(2)

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(d) The photograph shows the student releasing a card.

Give two ways that the student could improve the accuracy of his measurements.(2)

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(Total for question = 14 marks)Q15.A student investigates the vertical forces acting on the ends of a horizontal rulerwhen it supports a load.

The ruler hangs from two newtonmeters with a weight suspended from it as shown.

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(a) The student moves the weight along the ruler and records forces B and C bytaking readings from the newtonmeters.

(i) Which of these is the independent variable in this investigation?(1)

A Distance A

B Force B

C Force C

D Force D

(ii) Which of these is a controlled variable in this investigation?(1)

A Distance A

B Force B

C Force C

D Force D

(b) The student records these readings.

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She plots this graph to show how force C changes with distance A.

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(i) Complete the student's graph by labelling the vertical axis.(1)

(ii) Using the same grid and axes, plot a second line to show how force B varieswith distance A.

(3)(iii) Use the lines on the graph to find distance A for which force B and force C areequal.

(1)

Distance = ...................................... cm

(c) Suggest why neither force B nor force C are ever zero during the investigation.(1)

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Q16.The photograph shows a fruit seller using a yard-arm to weigh fruit.

The yard-arm consists of a steel bar about 1 m long, with a basket at one end and a moveable weight at the other end.

It is held up by a hook which is fixed to the bar close to the basket.

The diagram shows a yard-arm being used to find the weight of five bananas.

(a) Draw an X on the diagram to show the pivot point.

(1)(b) State the principle of moments.

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(c) The support for the basket is 14.1 cm from the pivot.

The moveable weight is 84.6 cm from the pivot and weighs 1.25 N.

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Calculate the weight of the five bananas.[ignore weight of steel rod and basket]

(3)

weight of five bananas = ........................................................... N

(d) Calculate the mass in grams of one banana.

(3)

mass of one banana = ........................................................... g

(e) Suggest two ways that the fruit seller could alter his yard-arm so that he could measure larger weights.

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(Total for question = 10 marks) Q17.A student investigates the extension of a rubber band when masses are added.

(a) Tick the boxes to select the correct items of apparatus that the student wouldneed in order to complete this investigation.

Two items have already been selected.(2)

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(b) The table below shows the student's results.

(i) Complete the table by inserting the missing force.(1)

(ii) Plot a graph to show how force varies with extension.(5)

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(iii) Use the information from the graph to explain whether the rubber bandobeys Hooke's Law.

(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................

(Total for question = 10 marks)Q18.A student wants to use a weighing scale to find the weight of her school bag.

She has a weighing scale marked in kilograms instead of newtons.

The weighing scale is not working properly.

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With nothing hanging from it, the weighing scale shows 1.5 kg.

(a) What is the weight of a 1.5 kg mass?(1)

Weight = ........................................................... N(b) The student decides to check the weighing scale.

She has no accurate weights.Instead, she puts some tins of beans in a plastic bag and hangs it from the scale.

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Her readings are shown in the table.

(i) Draw a graph to show how the scale reading varies with the number of tins ofbeans.

(5)

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(ii) Circle the anomalous point on your graph.(1)

(c) The student notices that the label on each tin says 'contains 0.4 kg of beans'.She remembers that six tins of beans gave a scale reading of 3.9 kg.

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She hangs her school bag from the weighing scale.The scale reading is 5.0 kg.She also concludes that her school bag must have a mass of exactly 3.5 kg.Suggest reasons why the student's conclusions might be incorrect.

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(Total for question = 11 marks)Q19.Photograph C shows how a student can use a claw hammer to pull a nail from a piece of wood.

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(a) The mass of the hammer is 0.454 kg.(i) Calculate the weight of the hammer.

(2)

Weight = ........................................................... N

(ii) From what point does this weight act?(1)

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(b) Photograph D shows the directions of two other forces on the hammer.

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(i) Draw an arrow on photograph D to show the force on the nail from the hammer.(2)

(ii) Suggest two ways that the student could increase the moment on the hammer.(2)

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(Total for question = 7 marks)Q20.A student uses this apparatus to investigate forces stretching a spring.

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She uses a ruler to measure the vertical distance h between the bottom of the mass hanger and the base of the stand.

(a) Suggest two ways that the student can measure distance h more accurately.

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(b) The student continues her investigation by loading the spring with different masses.

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The table shows her results.

(i) Name the dependent variable in this investigation.(1)

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(ii) Explain how the force values in the table are calculated.(2)

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(iii) Plot a graph of distance h against force, and draw the line of best fit.(5)

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(iv) Use your graph to find the force for which h is zero.(2)

force = .............................................. N

(v) Explain whether the spring obeys Hooke's law.(2)

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(Total for question = 14 marks) Q21.The diagram shows the side view of a laptop computer. of 56

A student opens the computer with an upward force of 4.2 N.

The force is applied 0.25 m from the pivot.

(a) (i) State the equation linking moment, force and distance.(1)

(ii) Calculate the moment of the force that opens the computer.(2)

Moment = ........................................................... N m

(b) The student finds that 4.2 N is the minimum upward force needed to open thecomputer.

Then the student applies a downward force, F, to close the computer.

Explain why the minimum force needed to close the computer is likely to be lessthan 4.2 N.

(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ..............................................................................................................................................(Total for question = 5 marks)Q22.A student investigates the principle of moments.

He connects a ruler to a stand with a pivot.

He hangs a 2 N weight from the 60 cm mark on the ruler.

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He uses a forcemeter to hold the ruler horizontal.The scale on the forcemeter reads from 0 N to 10 N.

(a) How could the student check that the ruler is horizontal?(2)

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(b) (i) State the equation linking moment, force and distance from the pivot.(1)

(ii) Calculate the moment of the 2 N weight.State the unit.(3)

Moment = ........................................................... Unit ...........................................................

(c) The student holds the ruler horizontal with the forcemeter at the 10 cm mark.He expects the reading on the forcemeter to be 12 N.The actual reading is 10 N.(i) Explain why the correct reading should be larger than 12 N.

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(ii) Explain why the actual reading is only 10 N.(1)

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(d) A picture in the student's textbook shows two fishermen using a pole to carry some fish.

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Fisherman A and fisherman B feel different forces on their shoulders.Use ideas about moments to explain why fisherman A feels the larger force.

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(a) The film is pulled through the camera using lever A.The student pushes on lever A with a force of 7.0 N.The force is applied 0.04 m from the pivot.(i) State the equation linking moment, force and distance.

(1)

(ii) Calculate the moment of the force that turns lever A and give the unit.(3)

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Moment = ........................................................... unit ...........................................................

(b) When all the film has been used, it is pulled back through the camera using lever R.

The force acting on lever R is only 0.02 m from its pivot.Explain why the minimum force needed to turn lever R is likely to be more than 7 N.

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(Total for question = 6 marks)Q24.(a) Which of these is a unit for the moment of a force?

(1)

A N

B N m

C N/m

D N/m2

(b) A painter sets up a uniform plank so he can paint a wall.

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The plank is 3 m long and weighs 500 N.(i) Use the principle of moments to show that the upward force A is 250 N.

(4)

(ii) State the value of force B.(1)

force B = ........................................................... N(c) The painter stands on the plank as shown.

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(i) Draw an arrow on the diagram to show the weight of the painter.(1)

(ii) Describe the changes in forces A and B when the painter stands on the plank.(2)

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Q25.The diagram shows a gate with a lever-operated catch.

A loop on the bolt fits around the lever-arm at A.

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(a) (i) Describe how the lever-arm is used to move the bolt.

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(ii) Suggest why the spring is needed.(1)

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(b) The lever-arm operates using the principle of moments.

(i) State the principle of moments.(1)

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(ii) The force applied at point B is 22 N.The pivot is 110 cm from point B and 38 cm from point A.Calculate the force exerted on the lever-arm at point A by the spring.

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force at point A = ........................................................... N

(iii) Explain how the force applied at point B would need to change if the distance from the pivot to point A is increased.

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(Total for question = 8 marks) Q26.A man uses a uniform plank to lift a block.He holds the plank horizontal.

The arrows on the diagram represent three forces on the plank.

(a) Complete the table to identify the missing force.

(1)

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(b) (i) State the equation linking moment, force and perpendicular distance from the pivot.

(1)

(ii) Calculate the clockwise moment of the block about the pivot.

(2)

moment = ........................................................... Nm

(c) Calculate the force of the man pushing down on the plank.

(4)

force = ........................................................... N

(Total for Question = 8 marks)Q27.(a) State the principle of moments.

(2) .............................................................................................................................................

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(b) A student uses the principle of moments to find the weight of a rock. This is the student's method.

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he balances a metre rule at its mid-point on a pivot he hangs a beaker from the 40 cm mark on the rule he places the rock in the beaker he then hangs a 0.2 N plastic strip from the rule on the other side of the pivot he adjusts the position of the plastic strip until the rule balances

(i)Describe how the student could use an electronic balance to check that the plastic strip weighs 0.2 N.(2)

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(ii) Suggest how the student could improve the precision of one of his measurements.(1)

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(iii) State the equation linking moment, force and perpendicular distance from the pivot.(1)

(iv) Use the principle of moments to calculate the force acting on the metre rule at the 40 cm mark.(3)

force = ........................................................... N

(v) Suggest a reason why the weight of the rock will be different from your calculated force.(1)

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(Total for question = 10 marks)Q28.A student makes chains of elastic bands by joining them together with paperclips.

He uses a newtonmeter to stretch each chain along a metre rule, as shown in photograph A.

For each chain, he records the number of elastic bands the length when the tension is 2 N the length when the tension is 1 NThen he calculates the difference in length for each chain.

(a) (i) Complete the table by calculating the missing value.(1)

(ii) Use the grid to plot a graph to show the relationship between the number ofelastic bands and the difference in length.

(5)

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(iii) Describe your line of best fit.(2)

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(b) Photograph B shows a paperclip in one of the chains against the same metre rule.

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Use photograph B to estimate the length of this paperclip.(2)

Length = ........................................................... cm(c) Look again at photograph A.

Suggest two ways that the student could improve his measuring technique.(2)

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physics7ar.files.wordpress.com · web viewhe balances a metre rule at its mid-point on a pivot he...

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