Forces and Energy Revision Booklet

Name: Year 7 Physics Unit 2 Revision List – Forces and Energy 1. Measuring forces a. Measuring pushes and pulls with Newton meters b. Forces can be represented by arrows 2. Mass a. b. c.

and weight Mass is how much matter something is made of Weight is how gravity affects the mass of an object A spring will extend evenly when the force is increased

3. Friction and air resistance a. Occurs between two surfaces b. Slows down or stops objects from moving c. A range of factors affect the frictional force 4. Density a. Density is how much matter there is in a given volume b. If the particles are closer together, the material is denser c. Materials less dense than water will float

5. Fossil fuels a. These are the remains of plants and animals that lived millions of years ago b. They include oil, gas, and coal c. They are non-renewable because once they are burned, they are gone d. They release carbon dioxide and carbon monoxide which are greenhouse gases 6. Renewable energy a. These are sources of energy which can be used over and over again b. Examples include: wind, solar, water (hydroelectric), and biofuels c. They do not release greenhouse gases and so are clean.

1. Measuring Forces Forces are nearly ALWAYS pushes and pulls.

1. Draw arrows on these pictures to show a push or a pull;

Forces can make objects do FIVE things: One example 1. Speed up

Kicking a football

2. Slow down

Putting on brakes

3. Change direction

Hitting a ball with a bat

4. Turn

Using a screw driver

5. Change shape

Making a snail out of blue tack

2. Complete the table above with your own examples.

Your own example

1. Measuring Forces Forces are nearly ALWAYS pushes and pulls.

1. What do we measure forces in?

2. Draw arrows and label them on this picture to show these four forces acting on the flying aeroplane: Gravity Air resistance Thrust Upthrust

Forces can make objects do FIVE things: 3. Complete the table below with your own examples.

Example Speed up Slow down Change direction Turn Change shape

1. Measuring Forces 1. Define what a force is and how we measure it:

2. Draw and label the four forces acting on this flying aeroplane;

3. Forces can make objects do five different things. One example is completed for you. Fill in the table below: Example Speed up

Kicking a football

Balanced forces produce no change in movement, while unbalanced forces change the speed or direction of moving objects.

4. Draw arrows to show whether the forces are balanced or unbalanced.

Bigger arrows = bigger force.

2. Mass and Weight Mass is how much matter (basically “stuff”) something is made out of.

Weight is how gravity affects the mass of an object and is a FORCE.



If you weigh yourself on the bathroom scales, you might be 50 kg.



This actually means that your MASS is 50kg.



Your WEIGHT is actually 500 N.

But if you went to a different planet, your WEIGHT would change! Would the amount of you change, i.e. your MASS? Yes / No

This table shows how much you would weigh on different planets.

Answer the questions related to the table: Planet

Gravity on planet

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

3.5 9 10 4 25 12 9 10 0.7

Your MASS (kg) 50 50 50 50 50 50 50 50 50

Your WEIGHT (N) 175 450 500 200 1250 600 450 500 35

1. Does your mass change on each planet?

2. On which other planet is your weight the same as on Earth?

3. Which planet do you weigh the most?

4. Which planet do you weigh the least?

2. Mass and Weight Mass is how much matter (basically “stuff”) something is made out of.

Weight is how gravity affects the mass of an object and is a FORCE.



If you weigh yourself on the bathroom scales, you might be 50 kg.



This actually means that your MASS is 50kg.



Your WEIGHT is actually 500 N.

But if you went to a different planet, your WEIGHT would change! Would the amount of you change, i.e. your MASS?

Yes / No

This table shows how much you would weigh on different planets.

You calculate the WEIGHT by multiplying GRAVITY X MASS. e.g. Mercury  Gravity X Mass = 3.5 X 50 = 175 Fill in the table and answer the questions: Planet

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

Gravity on planet 3.5 9 10 4 25 12 9 10 0.7

Your MASS (kg) 50 50 50 50 50 50 50 50 50

Your WEIGHT (N) 175 450

1. Does your mass change on each planet?

2. On which other planet is your weight the same as on Earth?

3. Which planet do you weigh the most?

4. Which planet do you weigh the least?

5. How do Moon Boots help astronauts walk on the moon?

2. Mass and Weight 1. What is MASS? 2. What is WEIGHT?



If you weigh yourself on the bathroom scales, you might be 50 kg.

 

This actually means that your MASS is 50kg.

Your WEIGHT is actually 500 N.

3. Why do you weigh less on the moon than on Earth?

This table shows how much you would weigh on different planets.

You calculate the WEIGHT by multiplying GRAVITY X MASS. Fill in the table and answer the questions: Planet

Gravity on planet

Your MASS (kg)

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

3.5 9 10 4 25 12 9 10 0.7

50 50 50 50 50 50 50 50 50

Your WEIGHT (N)

4. Does your mass change on each planet?

5. Which planet would it be most difficult to walk on?

6. Which planet would it be easiest to walk on?

7. How many times bigger is Jupiter’s gravity compared to Earth’s?

8. Explain why your WEIGHT changes but your MASS stay the same:

9. Describe what happens to a spring the more masses you add to it:

3. Friction and Air Resistance Friction is a force that tries to stop objects sliding past each other.  It allows us to start and stop  It stops us from falling over all the time, like we do on icy roads  It allows us to hold onto things (try holding a slippery fish!)

1. Show with arrows where FRICTION is on each of these pictures:

Air resistance is a force which acts against moving objects.  It slows down cars and planes  It allows us to jump out of a plane with a parachute 2. Show with arrows where AIR RESISTANCE is on each of these pictures:

3. Friction and Air Resistance Friction is a force that tries to stop objects sliding past each other.

1. Show with arrows where FRICTION is on each of these pictures:

Read these statements and cross out the wrong answer: 2. The surfaces with the most friction feel ROUGH/SMOOTH. 3. You can DECREASE/INCREASE friction using a lubricant.

4. The more friction there is, the MORE/LESS heat is made.

Air resistance is a force which acts against moving objects.

5. Show with arrows where AIR RESISTANCE is on each of these pictures:

Read these statements and cross out the wrong answer: 6. On the moon there IS/IS NOT any air resistance.

7. Streamlining is a way of REDUCING/INCREASING air resistance.

8. Surfaces which are most streamlined are ROUGH/SMOOTH.

3. Friction and Air Resistance 1. Define friction: 2. Give three examples of where friction is useful: i) ii) iii) 3. Give two examples of where friction is not useful: i) ii) 4. Give three ways of increasing friction: i) ii) iii) 5. Give two ways of decreasing friction: i) ii) 6. Define air resistance:

7. Give two examples of where air resistance is useful: i) ii) 8. Explain how air resistance is a type of friction:

9. Use an example to describe where streamlining is important: (you could draw a diagram)

4. Density Density is how much matter (stuff) there is in a given volume (space).

Something is denser (and will sink) if it has more matter in the same space.

1. Which one is most dense? Circle your answer:

2. Why did you think this?

 If the density of a material is more than for water, then it will sink.  If the density is less than water, then it will float.

The density of water is 1 g/cm3.

3. Look at this table and fill in the final column: Material Steel Wood Ice Diamond

Density (g/cm3) 7.6 0.8 0.9 3.5

Float or sink?

4. Density Density is how much matter (stuff) there is in a given volume (space).

Something is denser (and will sink) if it has more matter in the same space.

1. Which one is most dense? Circle your answer:

2. Why did you think this?

 If the density of a material is more than for water, then it will sink.  If the density is less than water, then it will float.

The density of water is 1 g/cm3.

3. Look at this table and fill in the final column: Material Steel Wood Polystyrene Ice Diamond Blood Mayonnaise Sea water Planet Saturn

Density (g/cm3) 7.6 0.8 1.05 0.9 3.5 1.035 1.0 1.025 0.6

Float or sink?

4. Density 1. Define density: Something is denser (and will sink) if it has more matter in the same space.

2. Fill in the boxes below to show the particles in a solid, liquid and gas:

solid liquid 3. Which is the most dense? Why?

gas

 If the density of a material is more than for water, then it will sink.  If the density is less than water, then it will float.

The density of water is 1 g/cm3.

4. Look at this table and fill in the final column: Material Steel Wood Polystyrene Ice Diamond Blood Mayonnaise Sea water Planet Saturn

Density (g/cm3) 7.6 0.8 1.05 0.9 3.5 1.035 1.0 1.025 0.6

Float or sink?

5. Ice is odd because it is a solid but it is less dense than water and floats.

What do you think might be going on?

5. Fossil Fuels Fill in the gaps using words in the box below:

Fossil took of years to form. Once we dig them out of the , we cannot get them back. This means that they are . One day we might not be able to any more and we will have . non-renewable run out

fuels

millions

ground

find

Carbon footprints  Our Carbon Footprint is how much energy we use.  It is important to reduce how much energy we use so we stop the planet from heating up too much.

Give three ways that you could reduce how much energy you use: 1.

2.

3.

5. Fossil Fuels Fossil fuels took millions of years to form from dead plants and animals.  Once we have dug them out of the ground, we cannot get them back.  This means that they are NON-RENEWABLE or we can’t get them back.  One day we might not be able to find any more, and we will have run out.

1. Why do you think it is important to turn off lights and the television when we are not using them?

Crude oil is a fossil fuel which can be used to make all sorts of useful plastics and medicines.

2. What would happen if we kept burning fossil fuels until they ran out?

Our Carbon Footprint is how much energy we use and therefore how much carbon dioxide we let into the atmosphere.

3. Carbon dioxide is a ‘greenhouse gas’. What does this mean?

4. If we keep burning fossil fuels and letting CO2 enter the atmosphere, what will happen to the Earth?

5. Fossil Fuels 1. Define what a fossil fuel is:

2. What does non-renewable mean?

3. Why do you think it is important to turn off lights and the television when we are not using them?

Crude oil is a fossil fuel which can be used to make all sorts of useful plastics and medicines.

4. What would happen if we kept burning fossil fuels until they ran out?

5. What is our Carbon Footprint?

6. Carbon dioxide is a ‘greenhouse gas’. What does this mean?

7. If we keep burning fossil fuels and letting CO2 enter the atmosphere, what will happen to the Earth?

6. Renewable energy 1. Match the energy source with the description:

WIND

Plants are grown and burnt to release heat energy to turn turbines

WAVES

Light is converted to electrical energy using special panels

SOLAR

Giant turbines spin round with this energy source to make electricity

BIOMASS

This energy source can use the energy in the sea to create electricity

2. What does a greenhouse do?

3. Carbon dioxide is a greenhouse gas.

This means it makes Earth a bit like a greenhouse. Why do you think this might be a bad thing?

6. Renewable energy Renewable energy resources won’t run out because they can be RENEWED. They cannot be reused, because you can’t burn a tree and use it again! But you can plant a new tree and burn that.

1. Describe how each of these resources are renewable:

Wind:

Solar:

Waves:

Biomass (plants):

2. Renewable energy resources don’t give off carbon dioxide like fossil fuels do. This means that they are CARBON NEUTRAL. Describe how it would benefit our planet if we stopped using fossil fuels and got all of our energy from renewable sources:

6. Renewable energy The sun is the source of all energy resources.

It reaches earth and is converted into many different forms.

Explain how this works for each of the below energy sources:

1. Fossil fuels

2., Biomass (e.g. wood)

3. Food

4. Wind power

5. Wave power

6. Solar power

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