P4 - Explaining Motion

Question 1

Give two units of speed

Answer 1

m/s and km/h

Question 2

Displacement

Answer 2

The distance an object is from its starting point

Question 3

Velocity

Answer 3

An object’s speed in a certain direction

Question 4

What is the speed equation?

Answer 4

Speed = distance / time

Question 5

What is the Average velocity equation?

Answer 5

Average velocity = displacement / time

Question 6

What is the displacement equation?

Answer 6

Displacement = Acceleration x Time

Question 7

Acceleration

Answer 7

The rate at which the speed of an object increases

Question 8

What is the Acceleration equation?

Answer 8

Acceleration = Change in speed / Time

Question 9

What are the units of Acceleration?

Answer 9

Metres per second squared = m/s^2 OR m/s/s

Question 10

What is another word for negative acceleration?

Answer 10

Deceleration

Question 11

What is a repulsive force? and what force does it oppose

Answer 11

A force which pushes objects apart and it works against an attractive force which pulls objects together

Question 12

What is the opposing force to gravity?

Answer 12

Reaction

Question 13

What are vector quantities?

Answer 13

Quantities like Forces that have both magnitude (size) and direction

Question 14

What is friction?

Answer 14

A force that acts on two surfaces as the slide over one another

Question 15

The size of the friction force depends on: (2)

Answer 15

• the roughness of the surfaces

- how hard they are pushed together/ how heavy they are

Question 16

Limiting friction

Answer 16

When friction reaches a certain maximum value and objects start the move

Question 17

Why is Lubrication used to reduce friction in machinery?(2)

Answer 17

To stop the parts getting too hot and wearing out

Question 18

How does friction work when you walk? (3)

Answer 18

Your feet push against friction so the floor pushes your foot forwards.
The resultant force is a combination of friction and the surface reaction
They combine to push the foot in a diagonal upwards direction

Question 19

Resultant force

Answer 19

The total or overall force acting on an object

Question 20

What is Newton’s first law?(3)

Answer 20

When resultant force = 0, the forces are balanced and acceleration is 0. The object will either:
•be still
•move continually at a constant speed

Question 21

What is Newton’s third law? (3)

Answer 21

When forces are unbalanced, an object will either have a:
•change in speed
•change in direction

Question 22

Gravity

Answer 22

A force which pulls all object towards the centre of the Earth

Question 23

What force opposes gravity when object are falling through the air?

Answer 23

Air resistance/ drag

Question 24

The ____ the object’s surface area, the _____ the drag force

Answer 24

Larger, larger :D

Question 25

Terminal velocity

Answer 25

The constant maximum speed reached by a falling object

Question 26

The size of the force exerted during a collision depends on: (3)

Answer 26

• the mass of the object
• the speed of the object
• the duration of the impact

Question 27

What are the four car safety devices?

Answer 27

Air bags, crumple zones, seat belts, crash helmets

Question 28

What do seat belts do to protect passengers? (2)

Answer 28

Stretch to increase the impact time

Hold a person in the car

Question 29

What do crumple zones do to protect passengers? (2)

Answer 29

Increase the time to stop, the impact force

Decrease the kinetic energy

Question 30

What do air bags do to protect passengers? (1)

Answer 30

Increase the time it takes for the momentum to reach 0

Question 31

What is the equation for momentum?

Answer 31

Momentum = mass x velocity

Question 32

What is the equation for change in momentum?

Answer 32

Change in momentum = resultant force x time which it acts

Question 33

What are the units of force?

Answer 33

Newtons

Question 34

What are the u it’s of momentum?

Answer 34

kg m/s

Question 35

Work done

Answer 35

The energy used by the movement of a force

Question 36

What are the units of work done?

Answer 36

Joules

Question 37

Energy + units

Answer 37

The ability to do work, measured in joules

Question 38

What is the equation for work done? With units

Answer 38

Work done(J) = Force(N) x Distance moved in the direction of the force (m)

Question 39

As you raise an object, the Gravitational potential energy _____ and as an object falls the gravitational potential energy ______

Answer 39

Increases as raised and decreases as falls

Question 40

What is the equation for change in GPE with units?

Answer 40

Change in Gravitational potential energy (J) = weight (N) x Vertical height (m)

Question 41

What is the equation for kinetic energy with units?

Answer 41

Kinetic energy (J) = 1/2 x Mass (kg) x Velocity squared (m/s^2)

Question 42

Remember this! :)

Answer 42

The work done by a force is the same as the change in kinetic energy

Question 43

When an object falls its ________ is transferred to ________

Answer 43

Gravitational potential energy is transferred to Kinetic energy

Question 44

What are the 5 energy changes when someone does a pole vault?

1. Running
2. Using the pole
3. Launching above the obstacle
4. Falling towards the ground
5. Landing on the ground

Answer 44

1. Kinetic energy
2. Elastic energy
3. GPE
4. Kinetic energy
5. Heat and Sound energy

Question 45

When a ball is bounced, when the ball is high the ____ is high and when the ball is the low the _____ is high

Answer 45

High ball = High GPE

Low Ball = High KE

Question 46

Speed

Answer 46

How far an object travels in a certain amount of time