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Flashcards in Motion And Forces Deck (27)
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1

Define a scalar.

It has magnitude but not direction

2

Define a vector.

Has both magnitude and direction

3

Name 3 scalars.

Distance
Speed
Mass
Energy

4

Name 3 vectors.

Displacement
Velocity
Acceleration
Force
Weight
Momentum

5

Define velocity.

Speed in a given direction

6

What is the main advantage of using light gates to measure time?

It eliminates human reaction time error

7

Define resultant force.

One force that replaces many forces

8

When two bodies interact, what can you say about the size and direction of the action and reaction force?

Equal and opposite

9

What will happen to an objects motion if the resultant force is not zero?

Stay at rest, or continue at a constant velocity

10

What will happen to an objects motion if the resultant force is zero?

Accelerate or decelerate

11

State Newton's First Law.

When a resultant force is zero a body is constant velocity or at rest. If the resultant force is not zero the body will accelerate

12

State two factors that will affect the acceleration of an object.

Size of resultant force
Mass of object

13

What is Newton's second Law?

Force = Mass x Acceleration

14

Describe the acceleration of a body free falling in a vacuum.

Constant acceleration (10m/s squared on Earth)

15

Describe the difference between mass and weight.

Weight is a force measured in Newtons. Mass is a measurement of the amount of matter, measured in kg. Weight changed dependant on the gravitational field strength.

16

Describe the velocity of an object moving in a circle.

The direction of an object moving in a circle is constantly changing therefore it's velocity is constantly changing

17

Why must there be a resultant force acting an object moving in a circle?

An object moving in a circle is constantly changing therefore it must be accelerating. For an object to accelerate it must have a force acting upon it

18

What is the name of the force acting on an object moving in a circle?

Centripetal force

19

What is inertial mass?

It is a measure of how difficult it is to change velocity of an object. Also defined as ratio of force over acceleration

20

What is Newton's third law?

For every action, there is an equal and opposite reaction. In every interaction, there is a pair of forces acting on the two objects. The forces are the same magnitude but different directions

21

What two factors make up the overall stopping distance of a car?

Thinking distance plus braking distance

22

State three factors that will increase the braking distance of a car.

Speed
Worn brakes
Worn tires
Poor condition of the road

23

State three factors that will increase the thinking distance of a car.

Speed
Tiredness
Alcohol
Drugs

24

Define momentum.

Momentum = Mass x Velocity

25

State Newton's second law in terms of momentum.

Force = change of momentum / time taken

26

State the conservation of momentum.

The momentum before the collision will be the same as the momentum after the collision

27

Explain how all of the following safety features act to reduce injuries: air bag, crumple zone, seatbelt.

Increase the time taken for the object to stop thereby reducing the rate of change of momentum and reducing force