Speed

Question 1

What is distance?

Answer 1

How far an object moves; a scalar quantity without direction.

Question 2

What is displacement?

Answer 2

A vector that includes the distance and direction from an object’s starting point to its finish point.

Question 3

What is velocity?

Answer 3

The speed of an object in a given direction; a vector quantity with magnitude and direction.

Question 4

True or False: An object’s velocity changes if its direction changes, even if its speed is constant.

Answer 4

True

Question 5

How can an object have a constant speed but changing velocity?

Answer 5

By moving in a circle, where its direction is always changing.

Question 6

What is acceleration?

Answer 6

The change in velocity of an object per second; a vector quantity.

Question 7

What is the unit of acceleration?

Answer 7

Metres per second squared (m/s²).

Question 8

What does negative acceleration indicate?

Answer 8

An object is slowing down; referred to as deceleration.

Question 9

Fill in the blank: Acceleration can be calculated using the formula: acceleration (m/s²) = - _______.

Answer 9

change in velocity (m/s) / time taken (s)

Question 10

What is uniform acceleration?

Answer 10

When the acceleration of an object is constant.

Question 11

What equation applies to objects with uniform acceleration?

Answer 11

(final velocity) - (initial velocity) = 2 x acceleration x distance; v² - u² = 2as.

Question 12

What is the formula to calculate distance travelled?

Answer 12

distance travelled (m) = speed (m/s) x time (s).

Question 13

What is the symbol for distance?

Answer 13

s

Question 14

What is the symbol for speed?

Answer 14

v

Question 15

What is average speed?

Answer 15

Total distance travelled (m) / total time taken (s).

Question 16

List some typical average speeds.

Answer 16

• Walking ~ 1.5 m/s
• Running ~ 3 m/s
• Cycling ~ 6 m/s

Question 17

What is a typical value for the speed of sound?

Answer 17

300 m/s

Question 18

What are drag forces?

Answer 18

Frictional forces that act on an object moving through a fluid (liquid or gas).

Question 19

Fill in the blank: Drag forces always act in the _______ direction to an object’s movement.

Answer 19

opposite

Question 20

How do drag forces depend on speed?

Answer 20

They increase with the object’s speed; greater speed results in greater frictional force.

Question 21

What factors do drag forces depend on?

Answer 21

The shape and size of the object.

Question 22

What is streamlining?

Answer 22

Reducing the drag an object experiences.

Question 23

What is the frictional drag force in air called?

Answer 23

Air resistance.

Question 24

What does a distance-time graph show?

Answer 24

How the distance travelled by an object travelling in a straight line changes with time.

Question 25

What does a downwards curve in a distance-time graph indicate?

Answer 25

Reducing speed.

Question 26

What does a horizontal line in a distance-time graph indicate?

Answer 26

Stopped.

Question 27

What does an upwards curve in a distance-time graph indicate?

Answer 27

Accelerating.

Question 28

What does a steep gradient straight line in a distance-time graph represent?

Answer 28

High constant speed.

Question 29

What is the relationship between the gradient of the line in a distance-time graph and the object's speed?

Answer 29

The gradient is equal to the object's speed.

Question 30

How can the speed at any time be found if the object is accelerating?

Answer 30

By calculating the gradient of a tangent to the curved line at that time.

Question 31

What does a velocity-time graph show?

Answer 31

How the velocity of an object changes with time.

Question 32

What does a horizontal line in a velocity-time graph indicate?

Answer 32

Constant velocity.

Question 33

What does a straight line in a velocity-time graph represent?

Answer 33

Constant acceleration.

Question 34

What does a curved line in a velocity-time graph indicate?

Answer 34

Changing acceleration.

Question 35

What is the relationship between the gradient of the line in a velocity-time graph and the object's acceleration?

Answer 35

The gradient is equal to the object's acceleration.

Question 36

What does the area under the line on a velocity-time graph represent?

Answer 36

The distance travelled (or displacement).

Question 37

What forces act on an object falling through a fluid?

Answer 37

Weight due to gravity and drag force.

Question 38

How does the drag force change as the object speeds up?

Answer 38

It gets bigger.

Question 39

What happens to the resultant force as the drag force increases?

Answer 39

It gets smaller.

Question 40

What happens to the acceleration of the object as it falls?

Answer 40

It decreases.

Question 41

What is terminal velocity?

Answer 41

The constant velocity a falling object reaches when the frictional force acting on it is equal to its weight.

Question 42

What is the acceleration of an object when it first begins to fall?

Answer 42

9.8 m/s².

Question 43

What occurs when the frictional drag force balances the weight of the object?

Answer 43

The object reaches terminal velocity.

Question 44

Fill in the blank: Terminal velocity is the constant velocity a falling object reaches when the _______ acting on it is equal to its weight.

Answer 44

[frictional force]