Forces

Question 1

What are 3 examples of contact forces?

Answer 1

normal contact force
tension force
friction force

Question 2

What are 3 examples of non-contact forces?

Answer 2

Gravitational force

Electrostatic force

Magnetic force

Question 3

What is the difference between vector and scalar?

Answer 3

Scalar quantities only have a magnitude and do not have a direction.

Vector quantities have both a magnitude and a direction.

Question 4

If all the forces acting on an object balance out, then we say that the object is in:

Answer 4

Equilibrium

Question 5

What are the 2 types of deformation of a spring?

Answer 5

elastic, inelastic

Question 6

What does elastic deformation mean?

Answer 6

an object returns to its original shape after the forces have been removed

Question 7

What is inelastic deformation?

Answer 7

an object does not return to its original shape after the forces have been removed

Question 8

What is an object’s spring constant?

Answer 8

a measure of how many Newtons of force it would require to stretch (or compress) the object by 1 metre.

Question 9

What are the units for spring constant?

Answer 9

N/m

Question 10

What is Hooke’s law?

Answer 10

F = ke
force = spring constant * extension

Question 11

What is an object’s elastic limit?

Answer 11

if you stretch an object past this limit it will start deforming inelastically

Question 12

A _____ spring constant means the spring is more firm.

A _____ spring constant means the spring is less firm.

Answer 12

higher
lower

Question 13

What is the formula for elastic potential energy?

Answer 13

energy = 0.5 * spring constant * extension^2

Question 14

In a force - extension graph, The gradient of the straight part of the graph tells us the:

Answer 14

spring constant

Question 15

In a force - extension graph, The area under the curve tells us the:

Answer 15

elastic potential energy

Question 16

In a force - extension graph, The point where the line goes from straight to curved is referred to as the:

Answer 16

Elastic limit
or
Limit of proportionality

Question 17

What is a moment?

Answer 17

the rotational or turning effect of a force.

Question 18

What is the formula for moment?

Answer 18

Moment = force * (perpendicular) distance

Question 19

What are the units for moment?

Answer 19

Nm

Question 20

What is equation for weight?

Answer 20

weight = mass * gravitational field strength

Question 21

What is the formula for pressure?

Answer 21

pressure = force/area

Question 22

What are the units for pressure?

Answer 22

Pascals (Pa)

Question 23

Which states of matter exert pressure?

Answer 23

all of them

Question 24

What is the formula for acceleration?

Answer 24

acceleration = change in velocity / time

Question 25

The gradient of a distance / time graph tells us:

Answer 25

speed

Question 26

What does a flat line on a distance / time graph tell us about the movement of an object?

Answer 26

the object is stationary

Question 27

What does a flat line on a velocity/time graph tell us about the object?

Answer 27

it is moving at a constant velocity

Question 28

The gradient of a velocity / time graph tells us:

Answer 28

The acceleration or deceleration of the object

Question 29

a straight diagonal line in a velocity/time graph shows us:

Answer 29

the object is accelerating

Question 30

On a velocity / time graph, the distance travelled is shown by:

Answer 30

The area under the curve

Question 31

What is the size of air resistance dependant on?

Answer 31

surface area and velocity

Question 32

We say an object has reached 'terminal velocity' when it is falling with a _________ velocity.

Answer 32

constant

Question 33

When is terminal velocity reached?

Answer 33

The weight has the same magnitude as the air resistance The resultant force is zero

Question 34

What is newton's first law?

Answer 34

a resultant force is required to change the motion of an object

Question 35

What is newton's second law?

Answer 35

F = MA the force is proportional to the objects acceleration

Question 36

What is newton's third law?

Answer 36

When two objects interact, the forces they exert on each other are Equal and opposite

Question 37

What is the normal contact force?

Answer 37

the equal and opposite force exerted by an object when in contact with it and when it doesn't move

Question 38

A person weighs 800 N and is standing on the ground. The ground is pushing upwards towards the person's feet. How many newtons is this force?

Answer 38

800N

Question 39

What is stopping distance?

Answer 39

the total distance a car travels from the moment when the driver first notices an obstruction, to when the car stops.

Question 40

Stopping distance equals:

Answer 40

Thinking distance + braking distance

Question 41

What are 3 things that may slow down a person's reaction time?

Answer 41

being distracted consuming alcohol tiredness

Question 42

What are 3 things that may increase braking distance?

Answer 42

Ice on the road Worn tyre tread Worn brakes

Question 43

What is breaking distance?

Answer 43

the total distance a car travels from the moment when the breaks are first applied, to when the car stops.

Question 44

if a vehicle drives twice as fast, what will happen to the breaking distance?

Answer 44

The breaking distance increases by four times

Question 45

what is the relation between breaking distance and vehicle speed?

Answer 45

If the vehicle speed increases by a factor of 2, then the breaking distance will increase by a factor 2 squared (2^2), so 4 fold. if increased by 3 it will increase by 3^2 (9) times

Question 46

Which factor affects both the thinking distance and the braking distance?

Answer 46

Speed of the vehicle

Question 47

What is the formula for momentum?

Answer 47

momentum = mass * velocity

Question 48

What are the units for momentum?

Answer 48

kg m/s

Question 49

The conservation of momentum principle states:

Answer 49

The total momentum before a collision is equal to the total momentum after the collision.

Question 50

What formula relates force to momentum?

Answer 50

force = change in momentum / time

Question 51

Which safety features of a car aim to slow the rate at which momentum is lost?

Answer 51

Crumple zones Air bags