Topic 2 - Motion and Forces

Question 1

What is a Vector?

Answer 1

A Vector has magnitude and direction.

Question 2

What is a Scalar?

Answer 2

A Scalar has just magnitude.

Question 3

Give an example of a Scalar quantity.

Answer 3

Speed, distance, time, mass, energy.

Question 4

Give an example of a Vector quantity.

Answer 4

Velocity, displacement, acceleration, force, momentum.

Question 5

What is the significance of the ‘0’ point in vectors?

Answer 5

It can be decided based on context, such as the bottom of a cliff.

Question 6

What does the gradient of a Displacement Time Graph represent?

Answer 6

Velocity.

Question 7

What does a negative gradient on a Displacement Time Graph indicate?

Answer 7

Returning back to the starting point.

Question 8

What does a horizontal line on a Displacement Time Graph indicate?

Answer 8

Stationary.

Question 9

What does the area under a Displacement Time Graph represent?

Answer 9

Nothing.

Question 10

What does a curved line on a Displacement Time Graph indicate?

Answer 10

Changing velocity (acceleration).

Question 11

What does the gradient of a Velocity Time Graph represent?

Answer 11

Acceleration.

Question 12

What does a negative gradient on a Velocity Time Graph indicate?

Answer 12

Deceleration.

Question 13

What does a horizontal line on a Velocity Time Graph indicate?

Answer 13

Constant speed.

Question 14

What does the area under a Velocity Time Graph represent?

Answer 14

Distance travelled.

Question 15

What is Average Speed?

Answer 15

Overall distance divided by overall time.

Question 16

How can constant speeds be determined?

Answer 16

Measure distance travelled and use a stopwatch for time.

Question 17

What is the formula for speed?

Answer 17

Speed = distance / time.

Question 18

What is the typical speed of walking?

Answer 18

~1.4 m/s.

Question 19

What is the acceleration due to gravity?

Answer 19

g = 10 m/s².

Question 20

State Newton’s First Law.

Answer 20

An object has a constant velocity unless acted on by a resultant force.

Question 21

What happens if a resultant force acts on an object?

Answer 21

It will accelerate.

Question 22

What is Newton’s Second Law?

Answer 22

Force = mass × acceleration (F = ma).

Question 23

How is weight measured?

Answer 23

Using a force meter or weighing scales.

Question 24

What is Circular Motion?

Answer 24

Object moving in a circle with constant speed but changing direction.

Question 25

What is centripetal force?

Answer 25

The force that supplies the acceleration for circular motion, directed towards the center.

Question 26

State Newton's Third Law.

Answer 26

Every action force has an equal and opposite reaction force.

Question 27

What is momentum?

Answer 27

Momentum = mass × velocity (p = mv).

Question 28

What is the principle of conservation of momentum?

Answer 28

Total momentum before a collision equals total momentum after.

Question 29

What is the average human reaction time?

Answer 29

0.25 seconds (250 milliseconds).

Question 30

List factors that affect reaction time.

Answer 30

* Concentration * Tiredness * Distractions * Influence of drugs/alcohol.

Question 31

What is Thinking Distance?

Answer 31

Distance travelled during reaction time.

Question 32

What factors affect Braking Distance?

Answer 32

* Poor road conditions * Bald tires * Worn brake pads * Mass of the vehicle.

Question 33

What is the relationship between speed and braking distance?

Answer 33

Braking distance ∝ (initial velocity)².

Question 34

What is the work done to stop a vehicle equal to?

Answer 34

The initial kinetic energy of the vehicle.

Question 35

What happens during a crash in terms of momentum?

Answer 35

There is a large deceleration resulting in a great force felt.

Question 36

What is the formula for force based on momentum change?

Answer 36

Force = change in momentum / time.

Question 37

What skills are needed for momentum calculations?

Answer 37

* Convert units * Interpret graphs * Calculate distance, speed, and time * Estimate stopping distances.