P9 - Motion

Question 1

What is the equation for speed?

Answer 1

speed = distance ÷ time

Question 2

What are the units of speed?

Answer 2

m/s (metres per second)

Question 3

What is average speed?

Answer 3

Total distance travelled divided by total time taken.

Question 4

What is instantaneous speed?

Answer 4

The speed of an object at a particular moment in time.

Question 5

What does a flat (horizontal) line on a distance–time graph show?

Answer 5

The object is stationary.

Question 6

How do you find speed from a distance–time graph?

Answer 6

Find the gradient: (change in distance) ÷ (change in time).

Question 7

What does a steeper line on a distance–time graph indicate?

Answer 7

A faster speed.

Question 8

What is velocity?

Answer 8

Speed in a given direction (a vector quantity).

Question 9

What is acceleration?

Answer 9

The rate of change of velocity.

Question 10

Equation for acceleration?

Answer 10

a = (v − u) ÷ t
v = final velocity, u = initial velocity

Question 11

Units of acceleration?

Answer 11

m/s²

Question 12

What does a positive gradient on a velocity–time graph show?

Answer 12

Acceleration

Question 13

What does a negative gradient on a velocity–time graph show?

Answer 13

Deceleration

Question 14

What does a flat line on a velocity–time graph show?

Answer 14

Constant velocity

Question 15

How do you calculate distance travelled from a velocity–time graph?

Answer 15

Find the area under the graph.

Question 16

What is terminal velocity?

Answer 16

When the driving force (e.g., weight) is balanced by resistive forces (e.g., air resistance), giving zero acceleration.

Question 17

What is displacement?

Answer 17

The distance travelled in a straight line from a starting point, with direction (vector).

Question 18

How are speed and velocity different?

Answer 18

Speed is scalar, velocity is vector.

Question 19

What affects the shape of velocity–time graphs?

Answer 19

Acceleration or deceleration of objects and changes in direction.

Question 20

How do you calculate final velocity using distance & acceleration?

Answer 20

v² = u² + 2as

Question 21

What is meant by uniform acceleration?

Answer 21

Acceleration that is constant.

Question 22

Give an example of uniform acceleration.

Answer 22

An object in free fall (ignoring air resistance).

Question 23

What is the typical value of acceleration due to gravity (g) on Earth?

Answer 23

Approximately 9.8 m/s²

Question 24

When is distance equal to displacement?

Answer 24

When the motion is in a straight line and does not change direction.

Question 25

What does the area under a uniform acceleration section of a velocity–time graph look like?

Answer 25

A triangle, so distance = ½ × base × height.

Question 26

What is the difference between a distance–time and velocity–time graph?

Answer 26

A distance–time graph shows speed, a velocity–time graph shows acceleration.

Question 27

What does a curved line on a distance–time graph indicate?

Answer 27

The object is accelerating or decelerating.

Question 28

What does a curved line on a velocity–time graph indicate?

Answer 28

Changing acceleration (non-uniform).

Question 29

What is the gradient of a velocity–time graph?

Answer 29

Acceleration

Question 30

What is the gradient of an acceleration–time graph?

Answer 30

The rate of change of acceleration

Question 31

What is the area under an acceleration–time graph?

Answer 31

Change in velocity

Question 32

What is relative velocity?

Answer 32

The velocity of one object compared to another.

Question 33

What happens to velocity if an object changes direction but keeps the same speed?

Answer 33

Its velocity changes because velocity depends on direction.

Question 34

What is meant by 'scalar quantity'?

Answer 34

A quantity with magnitude only (no direction).

Question 35

What is meant by 'vector quantity'?

Answer 35

A quantity with magnitude and direction.

Question 36

Give three vector quantities.

Answer 36

Velocity, acceleration, displacement.

Question 37

Give three scalar quantities.

Answer 37

Speed, distance, time.

Question 38

How can you tell if an object is accelerating on a distance–time graph?

Answer 38

The graph becomes steeper (curves upward).

Question 39

How can you tell if an object is decelerating on a distance–time graph?

Answer 39

The graph becomes less steep (curves downward).

Question 40

What happens if the resultant force on a moving object is zero?

Answer 40

It moves at a constant velocity.

Question 41

What does a completely vertical line on a distance–time graph represent?

Answer 41

Impossible motion — infinite speed (not physically possible).

Question 42

What does a velocity of zero on a velocity–time graph mean?

Answer 42

The object is stationary, but not necessarily at the same place (depends on previous motion).

Question 43

What is motion with drag (air resistance)?

Answer 43

Motion in which resistive forces increase with speed, leading to terminal velocity.

Question 44

What does terminal velocity look like on a velocity–time graph?

Answer 44

The graph becomes horizontal (acceleration = 0).

Question 45

Why does acceleration decrease as an object falls?

Answer 45

Air resistance increases with speed until it balances weight.

Question 46

What is the difference between speed and rate of change of distance?

Answer 46

No difference — they are the same definition.

Question 47

How can displacement be negative?

Answer 47

If the object moves in the opposite direction to the defined positive direction.

Question 48

What is the formula for average velocity?

Answer 48

average velocity = displacement ÷ time

Question 49

What is the typical reaction time for a human?

Answer 49

About 0.2 to 0.3 seconds

Question 50

What affects human reaction time?

Answer 50

Tiredness, alcohol, drugs, distractions.