Topic 2 - Force And Momentum

Question 1

What is a scalar quantity?

Answer 1

A quantity that only has a magnitude

A quantity that doesn’t have direction

Question 2

What is a vector quantity?

Answer 2

A quantity that has both magnitude and direction

Question 3

How can a vector quantity be represented?

Answer 3

Using vector arrows

Question 4

How do vector arrows represent vectors?

Answer 4

The length of the arrow represents the magnitude

The arrow points in the associated direction

Question 5

Give three examples of vector quantities

Answer 5

Velocity
Displacement
Force

Question 6

Give 6 examples of scalar quantities

Answer 6

Temperature 
Time 
Mass
Speed 
Distance
Energy

Question 7

What is velocity?

Answer 7

The speed of an object in a specific direction

Question 8

On a distance/time graph, what value does the gradient of the line represent?

Answer 8

The speed

Question 9

On a displacement/time graph, what value does the gradient of the line represent?

Answer 9

The velocity

Question 10

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

Answer 10

Draw a tangent to the curve at the required time

Calculate the gradient of the tangent

Question 11

State the equation for the average acceleration of an object

Answer 11

Acceleration = change in velocity/time taken

Question 12

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

Answer 12

By the area under the graph

Question 13

On a velocity time graph, what does the gradient of the graph represent?

Answer 13

The acceleration

Question 14

State the typical value for the speed of sound

Answer 14

330m/s

Question 15

What is the typical human walking speed?

Answer 15

1.5m/s

Question 16

What Is thesypical value for human running speed?

Answer 16

3m/s

Question 17

What is a typical value for human cycling speed?

Answer 17

6m/s

Question 18

What is the approx. Value for gravity on earth?

Answer 18

10m/s^2

Question 19

What is the name given to the single force that is equable to all the other forces acting on a given object?

Answer 19

The resultant force

Question 20

State Newton’s first law for a stationary object

Answer 20

If the resultant force on a stationary object is 0, the object will remain at rest

Question 21

State Newton’s first law for a moving object

Answer 21

If the resultant force on a moving object is 0, the object will remain at constant velocity

Question 22

State the defining equation for Newton’s second law

Answer 22

Resultant force = mass x acceleration

Question 23

State Newton’s second law in words

Answer 23

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

Question 24

What is weight?

Answer 24

The force that acts on an object due to gravity and the object’s mass

Question 25

What quantities does weight depend on?

Answer 25

The object’s mass | The gravitational field strength

Question 26

What is the unit used for weight?

Answer 26

Newton

Question 27

What is the unit used for gravitational field strength?

Answer 27

N/kg

Question 28

What piece of equit,ent can be used to measure an object’s weight?

Answer 28

A calibrated spring-balance or Newton meter

Question 29

When can an object travelling at a constant speed not have constant velocity?

Answer 29

When it is changing direction, for example moving in a circle

Question 30

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

Answer 30

Velocity can only be constant I’d the direction is constant In circular motion, the direction is continuously changing So velocity is constantly changing

Question 31

What is the resultant force that acts on an object moving in a circle called, and in which direction does it act?

Answer 31

Centripetal force | Towards the centre of the circle

Question 32

What is inertial mass?

Answer 32

A measure of how difficult it is to chang a given object’s velocity

Question 33

State Newton’s third law

Answer 33

Whenever two objects interact, the forces that they exert on each other are always equal and opposite

Question 34

State the equation for momentum

Answer 34

Mass x velocity

Question 35

What is the unit used for momentum?

Answer 35

Kim/s | Kilogram metres per second

Question 36

In a closed system, what can be said about the momentum before and after a collision?

Answer 36

They are equal

Question 37

State the equation for change in momentum

Answer 37

Force x time

Question 38

How can you measure human reaction times?

Answer 38

Using the ruler drop test

Question 39

What is the regular drop test?

Answer 39

Person A and B hold each end of a ruler with the 0cm mark at the bottom Person A drops the ruler without telling person B Person B catches it The distance travelled corresponds to their reaction time

Question 40

Why is it important that the 0cm mark is at the bottom?

Answer 40

So you can see the distance directly without having to calculate it; otherwise a zero error would need to be accounted for

Question 41

What is the stopping distance of a vehicle equal to?

Answer 41

The sum of the thinking distance and braking distance

Question 42

For a given braking distance, if the vehicle’s speed is increased, what can be said about its stopping distance?

Answer 42

The stopping distance is increased with an increase in speed

Question 43

Give a typical range of values or human reaction time

Answer 43

0.2 seconds - 0.9 seconds

Question 44

Give four factors which can affect a driver’s reaction time

Answer 44

Tiredness Drugs Alcohol Distractions

Question 45

Give two factors which may affect braking distance

Answer 45

Condition of the car (brakes) | Weather conditions

Question 46

Describe the energy transfers that take place when a car applies its brakes

Answer 46

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

Question 47

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

Answer 47

It must also be increased

Question 48

State two consequences of a vehicle undergoing very large decelerations

Answer 48

Loss of control of the vehicle | Kinetic energy converted to heat is very high causing brakes to overheat