Physics

Final Exam Review

True or False?

The horizontal component of a projectile's velocity is

independent of the vertical component

Answer

TRUE

• After a rock that is thrown straight up reaches the top of its path and is starting to fall

back down, its acceleration is (neglecting air resistance) __?

___

Answer

• 10 m/s2 which is gravity (pulling downward)

A plane flying north at 50 km/h experiences a wind 10 km/h

south. What is the magnitude and direction of the plane?

Answer

• This is a headwind; therefore, you subtract.

• The answer is 40 km/h going north

• A plane flying north at 50 km/h experiences a wind 10 km/h east. What is the magnitude and direction of the plane?

Answer

• Use Pythagorean Theorem• a2 + b2 = c2

The answer is 51 km/h northeast

• When an object is thrown in a curved path, what is its velocity at the top of the path?

Answer

• Entirely horizontal because the vertical component is zero

• Assuming the car starts from rest, what is the acceleration if the car has a speed of 20 m/s for 4 s?

AnswerUnknown aKnown v = 20 m/s t = 4 s

a = v/t

5 m/s2

How high is a tree if an acorn falls and hits the ground in 2.25 s?

Answer

Unknown d = vot + ½ gt2

d

Known = 0(2.25s) + ½ (10m/s2)(2.25s)2

t = 2.25 s = 0 + 5m/s2(5.0652s2)

d = 25.31 m

Question

• When a balloon deflates, the balloon pushes on the air and _______.

Answer

• The air pushes on the balloon

Question

• A book weighs 10 N. When held at rest in your hands, the net force on the book is ____.

Answer

• Zero

Question

• As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?

Answer

• The pull of the ball’s mass on the Earth

Question

• The outside force that slows objects down or stops their motion is ___.

Answer

• Friction

Question

• What is the pressure exerted on a table by a book that weighs 35 N and covers an area of 3 m2?

AnswerKnownF = 35 NA = 3 m2

UnknownP

EquationP = F A

SolveP = 35 N 3m2

P = 11.67 N/m2 or 11.67 Pa

Question

• A dog walks on a street. What is the force of friction between the 225 N dog and the street that has a coefficient of friction of 0.26?

AnswerKnownw = 225 N = FN

µ = 0.26

UnknownFf = ?

EquationFf = µFN

SolveFf = µFN

Ff = (0.26)(225N)

Ff = 58.5 N

Question

• Mass and acceleration are __________________ proportional.

Answer

• Inversely proportional–More mass results in less acceleration

–Less mass results in more acceleration

Question

• Pressure and Area are _______________ proportional.

Answer

• Inversely proportional–More area covered results in less pressure

–Less area covered results in more pressure

Question

• Which has greater tangential speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?

Answer

• The one on the outside because it has a larger radius

a. depth of the measuring pointb. mass of the liquidc. volume of the liquidd. density of the liquide. both A and D

____ 1. Pressure in a liquid depends on the _____.

Answer

EThe depth and the density

a. weight of the fluid displacedb. mass of the fluid displacedc. volume of the fluid displacedd. mass of the objecte. none of the above

Archimedes' principle says that an object is buoyed up by a force that is equal to the _____.

Answer

A

weight of the fluid displaced

• What is the difference in water pressure between the top and bottom of a 100-m deep well?

Answer

• At the bottom the pressure is greater

• If you lift four loads up one step, how much work do you do compared to lifting two loads up one step.

Answer

• You do twice as much workW = Fd,

therefore, if the distance stays the same but you lift twice as much weight, you do twice as much work

• What is the buoyant force of a rubber ducky floating in water that displaces 0.05 cm3 of water. (remember the density of water is 1 g/cm3)

AnswerKnownD = 1 g/cm3

g = 10 m/s2

V = 0.05 cm3

UnknownFb

EquationFb = DgV

SolveFb = DgV =(1g/cm3)(10m/s2)(0.05cm3)

Fb = 0.5 N

• Draw a parallel and series circuit with three resistors. Label the resistors, wire and battery.

Answer

• Series Parallelwire

battery

• The Tacoma Bridge collapsed due to the alignment of frequencies between the bridge and the wind which is called ___.

Answer

• Resonance

• Which is the angle of reflection?

• Which is the angle of reflection?

– Angle C

• Which is the angle of reflection?

• Which is the angle of incidence?

– Angle B