Forces and Motion

Question 1

Average Speed equals

Answer 1

Total Distance/Total Time

Question 2

Is Speed a scalar quantity?

Answer 2

Yes

Question 3

Examples of Scalar Quantities

Answer 3

Distance, Speed, Time, Energy

Question 4

Is Velocity a scalar quantity.

Answer 4

No. It is a vector quantity as it has magnitude and direction.

Question 5

Acceleration equals

Answer 5

Change in velocity/time

Question 6

v squared =

Answer 6

u squared + 2as (where s is displacement)

Question 7

Examples of vector quantities

Answer 7

Displacement, Velocity, Acceleration, Force

Question 8

On a Distance - Time graph, the gradient is equivalent to

Answer 8

Velocity

Question 9

On a Velocity - Time graph, the gradient is equivalent to

Answer 9

Acceleration

Question 10

On a Velocity - Time graph, the area under the graph is equivalent to

Answer 10

Distance travelled

Question 11

Newton’s First Law

Answer 11

an object has a constant velocity unless acted on by a resultant force

Question 12

Newton’s Second Law

Answer 12

F = ma

Question 13

Newton’s Third Law

Answer 13

Every action force has an equal and opposite reaction force

Question 14

Mass measures

Answer 14

the amount of matter in an object

Question 15

Weight =

Answer 15

Mass x Gravitational field strength

Question 16

Explain what happens (in terms of forces and acceleration) as an object is released from rest and then falls under gravity

Answer 16

1. Object begins to accelerate as the force downwards due to gravity is greater than the force opposing motion due to air resistance.
2. As the speed increases, so the air resistance increases.
3. When the air resistance is equal to the force due to gravity then the forces are in equilibrium and the body will move at a constant velocity.

Question 17

Thinking distance is

Answer 17

the time between seeing the hazard and starting to brake

Question 18

Braking distance is

Answer 18

the time between pressing the brake pedal and stopping

Question 19

Stopping distance is

Answer 19

Thinking distance + Braking distance

Question 20

Thinking distance depends on

Answer 20

1. Speed
2. Alertness (e.g. tiredness, alcohol)

Question 21

Braking distance depends on

Answer 21

1. Speed
2. Mass of vehicle
3. Road conditions
4. Tyres

Question 22

Deformations is

Answer 22

when a force produces a change in size or shape of a body

Question 23

Elastic deformation is

Answer 23

when the body returns to its original size and shape after deformation

Question 24

Hooke’s Law

Answer 24

Force = Spring constant x Extension (F = kx)

Question 25

On a Force - Extension graph of a spring

Answer 25

1. The initial straight part is the Elastic Region
2. The end of the initial straight part is the limit of proportionality
3. The curved part is the plastic region
4. The end of the curved part is when the body/spring fractures

Question 26

Moment equals

Answer 26

Force x Perpendicular distance from the pivot

Question 27

Moment is a measure of

Answer 27

turning effect

Question 28

Moment is measured in

Answer 28

Nm

Question 29

If the sum of the clockwise moments equals the sum of the anticlockwise moments, then the body is

Answer 29

In equilibrium

Question 30

Momentum equals

Answer 30

Mass x Velocity

Question 31

Momentum is measured in

Answer 31

kgm/s

Question 32

Force equals

Answer 32

change in momentum/time

Question 33

To increase safety in a car

Answer 33

force is reduced by increasing time for a given momentum change - e.g. car seat belt or air bag

Question 34

The six contact forces are

Answer 34

1. Friction
2. Air-resistance
3. Tension
4. Spring force
5. Applied force
6. Normal force
   FAT SAN

Question 35

The three action at a distance forces are

Answer 35

1. Gravitational
2. Electrical
3. Magnetic

Question 36

In a collision, momentum is always

Answer 36

conserved