Force and Motion

Question 1

State a typical value for the speed of sound

Answer 1

330 m/s

Question 2

What is a typical value for human walking speed?

Answer 2

1.5 m/s

Question 3

What is a typical value for human running speed?

Answer 3

3 m/s

Question 4

What is a typical value for human cycling speed?

Answer 4

6m/s

Question 5

State the equation linking speed, distance and time.

Answer 5

Distance (m) = Speed (m/s) x time (s)

Question 6

Why can an object travelling at a constant speed in a circle not have a constant velocity?

Answer 6

Speed is a scalar, velocity is a vector quantity which means it can only be constant if the direction is constant

Question 7

How can speed be calculated from a distance-time graph?

Answer 7

Speed = gradient of graph

Question 8

What must be done to calculate the speed at a given time from a distance-time graph for an accelerating object?

Answer 8

Draw a tangent to the curve at the required time
Calculate gradient of the tangent

Question 9

State the equation for the average acceleration of an object

Answer 9

Acceleration = Change in velocity / Time taken

Question 10

How can distance travelled by an object be calculated from a velocity time graph?

Answer 10

It is equal to the area under the graph

Question 11

Value for acceleration of an object in free fall under gravity near earths surface

Answer 11

9.8 m/s

Question 12

What can be said about the resultant force acting on an object when it is falling at terminal velocity?

Answer 12

The resultant force is zero
When at terminal velocity object is moving at constant speed so there is no acceleration

Question 13

State Newton’s first law for a stationary object

Answer 13

If resultant force on it is zero, the object will remain at rest

Question 14

State Newton’s first law for a moving object

Answer 14

If resultant force is zero, the object will remain at constant velocity

Question 15

Braking forces = ______ forces

Answer 15

Driving

Question 16

If an object changes direction but remains at constant speed, is there a resultant force?

Answer 16

Yes because there is a change in direction, there is a change in velocity so there must be a resultant force.

Question 17

Defining equation for Newton’s Second Law.

Answer 17

F = ma
Resultant force = Mass x Acceleration

Question 18

State Newton’s second law.

Answer 18

An objects acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass.

Question 19

What is inertial mass?

Answer 19

A measure of how difficult it is to change a given objects velocity.

Question 20

Give the symbol used to represent an approximate value

Answer 20

~

Question 21

If a vehicles speed is increased, what can be said about its stopping distance?

Answer 21

Stopping distance Increases with an increase in speed

Question 22

Give a typical range for human reaction time.

Answer 22

0.2 seconds -> 0.9 seconds

Question 23

Give 3 factors which can affect a driver’s reaction time.

Answer 23

Tiredness
Drugs
Alcohol

Question 24

Give 2 factors which may affect a braking distance

Answer 24

Road conditions
Tire/ car conditions

Question 25

Describe energy transfers that take place when a car brakes.

Answer 25

Work is done by friction force between brakes and wheel Kinetic energy of wheel converted to heat and dissipated to surroundings

Question 26

To stop a car in a given distance, if its velocity is increased, what must happen to the braking force applied?

Answer 26

Must also be increased

Question 27

State two consequences of a vehicle undergoing very large decelerations

Answer 27

Kinetic energy converted to heat causing brakes to overheat Loss of control of vehicle

Question 28

What is a centripetal force?

Answer 28

The resultant for e when things are moving in a circle.