PS-5 Test Review

Questions 1 & 2

Distance – 60m/ magnitude only

Displacement 10 m east/ magnitude and direction

Question 3

Speed- distance an object moves per unit of time

Velocity- speed with direction

V = d/t

Questions 4, 5, & 6

They are rates as they measure a change in distance over time

Instantaneous

average

Question 7

speed- 30 m/s 50 km/ hr

Velocity- 30 m/s west 50 km/hr north

Question 8 & 9

135 km/ 7 hrs = 19.3 km/hr north

D = 25 m/s x 6 s = 150 m

Question 10

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Question 11 & 12

Rate of change in velocity

It does not have a constant velocity as it is constantly changing direction

It is accelerating as it’s velocity is changing

Questions 13 & 14

A = 15 km/hr/ 1s = 15 km/hr/s

Speed up, slow down, change directions

Questions 15 and 16

40km/hr – 0km/hr / 5s = 8km/hr/s

50km/hr – 0km/hr / 5s = 10km/hr/s

Car B accelerates fastest

1st row- no motion, constant velocity

2nd row- constant velocity, positive acceleration

3rd row- positive acceleration, negative acceleration

Questions 17 & 18

“g” = 9.8m/s2 and is acceleration due to gravity

9.8 x 2 = 19.6 m/s

Questions 19 & 20

Newton’s 1st law defines inertia as it describes an object’s resistance to change in motion

Inertia is resistance to change in motion

Example: a car crash

Questions 21 & 22

A force is a push or a pull and is measured in Newtons

Balanced force- net force of 0, objects’ motion does not change

Unbalanced force- net force that accelerates an object

Net force- the sum of all forces acting on an object

Question 23

The acceleration of an object is dependent on the force applied and the mass of the object.

To accelerate an object the force must be applied in the same direction as the acceleration.

Questions 24 & 25

F = 1500kg x 2.5 m/s2 = 3750N

M = 500N / 2.0 m/s2 = 250 kg

Question 26

Mass is the amount of matter in an object. It is constant and is measured in kg

Weight is the measure of the pull of gravity on an object. It is a force and is measured in Newtons.

Questions 27 & 28

W = mass x 9.8m/s2 ( W = mg)

M = weight / 9.8m/s2 (M = w/g)

Inertia is NOT dependent on gravity because inertia is determined by mass and mass is a constant.

Questions 29 & 30

Gravity is the force of attraction between all objects in the universe.

Gravitational attraction depends on the mass of the 2 objects and the distance between them

There is not enough mass

Question 31

For every action there is an equal and opposite reaction.

Question 32

The swimmer pushes on the water and the water pushes back

The ball pushes on the wall and the wall pushes back.

The diver pushes down on the raft and the raft pushes back.

The person pushes on the wall and the wall pushes back.

Questions 33-35

Air resistance pushes up as gravity pulls down.

Friction is the force that opposes motion between 2 objects that are touching.

An object in free fall has no other force acting on it but gravity.