Forces and motion

Question 1

Put the correct words into the speed formula triangle

Answer 1

Speed
Distance
Time

Question 2

What are the three most common units of speed

Answer 2

m/s metres per second
mph miles per hour
km/h kilometres per hour

Question 3

What is a force?

Answer 3

A push or a pull

Question 4

What is the SI unit for force

Answer 4

Newtons (N)

Question 5

What instrument measures a force

Answer 5

A newton meter

Question 6

Identify the 5 actions which are the result of applying a force

Answer 6

1. Speed up or move more quickly
2. Slow down or stop moving
3. Change direction
4. Turn
5. Change shape

Question 7

What type of forces produce no change in movement

Answer 7

Balanced forces

Question 8

What type of forces produce a change in movement

Answer 8

Unbalanced forces

Question 9

Describe deforming

Answer 9

Changing the shape of something by applying a force

Question 10

Describe the action of a spring when a force is applied

Answer 10

The spring will deform by stretching or compressing when a force is applied
Springs are elastic- they usually spring back to their original shape

Question 11

What does the k stand for in Hooke’s law

Answer 11

k = spring constant

Question 12

What does the F stand for in Hooke’s law

Answer 12

F = force

Question 13

What does the e stand for in Hooke’s law

Answer 13

e = extension

Question 14

What is the formula for Hooke’s law

Answer 14

F = K x e

Question 15

How do two springs acting in series act?

Answer 15

The two springs are joined together and extend the same amount as each individual one would with the same force
eg two springs 10cm long would extend 20cm

Question 16

How do two springs acting in parallel act?

Answer 16

The two springs are next to each other and each extends half the amount than an individual would with the same force
eg 2 springs 10cm long would extend 5cm

Question 17

Which direction does friction always act in?

Answer 17

The opposite direction to movement

Question 18

Give some examples of the positive action of friction when riding a bike

Answer 18

It allows you to start, slow down and stop when you are on a bike
It allows the tyres to grip the road so you can move forward
It acts at the brakes as they grip the wheel rim making you slow down/stop
It allows you to grip the handlebars so you stay on

Question 19

Describe friction

Answer 19

It is a force which acts between surfaces trying to stop objects sliding past each other.

Question 20

Give some examples of the negative action of friction when riding a bike

Answer 20

Friction always wastes energy so the some of effort you put into to riding your bike will be wasted and limits your top speed
Friction between the moving parts of the bike wastes energy
Air resistance is a type of friction and this slows you down as well.
Top cyclists try to overcome air resistance with their clothing and helmet design being the most aerodynamic that they can. It is also why they try and cycle as close behind someone as they can.

Question 21

Explain what air and water resistance do to moving objects

Answer 21

They slow them down.
Sometimes called drag air and water resistance push against a moving object in the opposite direction to the movement
They a type of frictional force
Cars boats aeroplanes and other moving objects which need to move fast are designed to be streamlined to slip through the air or water with too much resistance.

Question 22

Explain how a parachute slow down a person falling through the air.

Answer 22

1. Without a parachute the air resistance of the person is a smaller force than the weight (gravity) acting down and so the person falls faster.
2. When the parachute opens the air resistance increases and is now larger than the weight and so the person slows down
3. The air resistance and the weight become balanced and so the person falls at a steady speed.
4. When the persons lands the force acting up from the ground balances their weight.

Question 23

Identify the two factors which make up stopping distance in a vehicle.

Answer 23

1. Thinking distance
2. Braking distance

Question 24

Explain the factors which can affect thinking distance when stopping a vehicle

Answer 24

1. Speed, the faster you are moving the further the vehicle will travel
2. Driver awareness, How much attention you are paying. This is affected by alcohol, drugs, tiredness and sometimes distractions

Question 25

Explain the factors which can affect braking distance when stopping a vehicle

Answer 25

1. Speed - the faster you are going the longer it takes to stop
2. Brakes - if the brakes are worn out they will not work as effectively
3. Tyre quality - worn tyres do not grip the road as much so less friction
4. Weather conditions - water snow and ice decrease the friction on the road surface
5. The road surface, some surfaces are more grippy but leaves, oil spills, muck on the road all reduce friction.