1 Forces and Motion

Question 1

Equation for speed

Answer 1

Distance/time

Question 2

Practical: investigate the motion of everyday objects such as toy cars or tennis balls

Answer 2

1. Connect a trolley to a ticker tape timer (fitted with a ticker tape) and position on a slope
2. Release the trolley.
3. Take a 5-dot section
4. Work out distance of this section
5. Divide by 50 (ticker tape timer is set to 50 times per second)

Question 3

Equation for acceleration

Answer 3

Change in velocity (final - initial)/time

Question 4

Distance - Time Graphs

Answer 4

Gradient = velocity

Question 5

Velocity - Time Graphs

Answer 5

Gradient = acceleration
Area under graph = distance or displacement

Question 6

Equation for final speed

Answer 6

v2 = u2 + (2 × a × s)

Question 7

Vector Quantities

Answer 7

Has magnitude + direction

Question 8

Scalar Quantities

Answer 8

Has magnitude

Question 9

Pulling Force

Answer 9

Tensile Force

Question 10

Pushing Force

Answer 10

Compressive Force

Question 11

What is the length of the arrow proportional to?

Answer 11

The size of the force

Question 12

Forces acting on an object

Answer 12

• Weight
• Friction
• Reaction force (opposes weight)

Question 13

Friction

Answer 13

Force that opposes motion

Question 14

Resultant Force

Answer 14

front force - back force
* If positive = acceleration
* If negative = deceleration

Question 15

How can frictional forces occur?

Answer 15

• When one surface rubs against another surface
• When a body moves through a fluid

Question 16

Investigating Friction

Answer 16

1. Put masses in shoe
2. Hook shoe to force meter
3. Pull force meter

Question 17

Equation for force

Answer 17

Mass x Acceleration

Question 18

Equation for Weight

Answer 18

Mass x Gravitational Field Strength

Question 19

Equation for stopping distance

Answer 19

Thinking Distance + Braking Distance

Question 20

What is friction in relation to weight?

Answer 20

Directly proportional

Question 21

Weight

Answer 21

• The force in which gravity pulls it down

Question 22

Factors that increase thinking distance

Answer 22

• High initial velocity
• Alcohol + drugs
• Tiredness
• Distraction inside car

Question 23

Factors that increase braking distance

Answer 23

• Poorly maintained brakes
• High initial velocity
• Road condition/surface
• Worn tyres

Question 24

Newtons 2nd Law

Answer 24

When an object experiences a resultant force it will accelerate. The magnitude of the acceleration is proportional to the force

Question 25

How an object reaches terminal velocity

Answer 25

1. There is an unbalanced force 2. W>D so acceleration 3. W=D so no acceleration so constant terminal velocity **After parachute opens** 4. W

Question 26

Equation for momentum

Answer 26

Mass x velocity

Question 27

Conservation of momentum

Answer 27

Provided there are no external forces on a system, total momentum is conserved. Momentum before = Momentum after

Question 28

Momentum for safety features

Answer 28

If time taken can be increased for a change in momentum, the force on the body can be decreased. This is done by airbags with inflate quickly and deflate slowly as the person hits them to slow them down

Question 29

Equation for force in terms of momentum

Answer 29

Change in momentum/time

Question 30

Hooke's Law

Answer 30

The extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality

Question 31

The limit of proportionality in Hooke's Law

Answer 31

if more force is added, the object may extend but will not return to its original shape when the force is removed (it will be **inelastically deformed**)

Question 32

Elastic behaviour

Answer 32

the ability of a material to recover its original shape after the forces causing deformation have been removed

Question 33

Practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands

Question 34

Newton's 3rd Law

Answer 34

To every force there is an equal and opposite reaction

Question 35

Equation for moment

Answer 35

Moment = force x perpendicular distance from the pivot

Question 36

Where does the weight of a body act from?

Answer 36

Its centre of gravity

Question 37

Principle of moments

Answer 37

Clockwise moment = anticlockwise moment

Question 38

What do forces cause?

Answer 38

A change in motion

Question 39

What factors affect drag?

Answer 39

* Velocity * Surface Area

Question 40

Axis on Hooke's Law graph

Answer 40

x - axis: Force y - axis: Extension

Question 41

Does a wire obey Hooke's law?

Answer 41

Initial yes, but then goes up on graph

Question 42

Does an rubber band obey Hooke's law?

Question 43

How are the independent variable and the dependant variable placed on the axis of a graph

Answer 43

* Independent variable: x - axis * Dependant variable: y - axis

Question 44

What type of graph does a continuous variable need?

Answer 44

Scatter graph

Question 45

How to work out the gradient

Answer 45

Up/accross

Question 46

How to find the centre of gravity of an irregular shape

Answer 46

1. Take a mounted needle with a plumb line attached to it 2. Place the mounted needle at the top and draw where the plumb line goes 3. Rotate and repeat 4. The point of intersection is the centre of gravity

Question 47

What is a moment?

Answer 47

The turning effect of a force

Question 48

When does the principle of moments apply?

Answer 48

When an object is balanced or in equilibrium