Forces

Question 1

What are the 8 main energy stores and give examples of each.

Answer 1

Chemical - fuel, food, battery
Kinetic - moving objects
Gravitational potential - raised mass
Elastic - stretched spring
Thermal - hot object
Magnetic - two magnets
Electrostatic - two charges
Nuclear - radioactive decay

Question 2

How is wasted energy lost?

Answer 2

Heat dissipation, sound energy dissipation, vibration

Question 3

Name 5 renewable energy sources.

Answer 3

Bio-fuels, hydroelectricity, wind turbines, tidal power, solar cells

Question 4

How do bio-fuels create energy?

Answer 4

Bio-fuels are animal or plant matter used to produce thermal energy, electrical energy or used to power cars.

Question 5

How is hydroelectricity used to create energy?

Answer 5

Hydroelectricity generates electricity from water behind a dam flowing down a pipe and turning a turbine to generate electricity.

Question 6

How are wind turbines used to create energy?

Answer 6

Wind turbines use kinetic energy from wind to generate electricity.

Question 7

How is tidal power used to create energy?

Answer 7

Tidal power uses the rise and fall of the tide or tidal currents to generate electricity.

Question 8

How are solar cells used to create energy?

Answer 8

Solar cells convert solar energy, or energy from the Sun, directly to electricity. Solar energy can also be used directly to cook food or heat water.

Question 9

What is the benefit of renewable energy sources?

Answer 9

Renewable energy sources will not run out. Most do not cause pollution or emit carbon dioxide.

Question 10

Name the non-renewable energy sources.

Answer 10

Fossil fuels (coal, oil, gas) - used to generate electricity, power transport, heat homes and for cooking.
Nuclear fuels such as uranium - used to generate electricity and as energy sources in spacecraft.

Question 11

What is a benefit of non-renewable energy sources?

Answer 11

They are available all the time unlike some renewable energy sources.

Question 12

Why is some energy always wasted?

Answer 12

Some energy is dissipated to the surroundings as heat or sound.

Question 13

How do you increase efficiency?

Answer 13

Reduce wasted energy using lubrication, insulation, or streamlined shapes.

Question 14

How do forces produce rotation?

Answer 14

A force applied at a distance from a pivot creates a turning effect.

Question 15

What is a moment?

Answer 15

The turning effect of a force around a pivot.

Question 16

What is the principle of moments?

Answer 16

For an object in equilibrium, total clockwise moments = total anticlockwise moments.

Question 17

How do you investigate the effect of mass on the acceleration of a trolley?

Answer 17

Apparatus: trolley, light gates, data logger, card of known length, slope or ramp, masses.

Method:
1) Set up apparatus.
2) Set up light gates to take velocity and time readings for you.
3) Record velocity and time for different values of mass on the trolley.
4) Work out acceleration by dividing the difference in the velocity values by the time taken for the card to pass between both gates.
5) If you are changing the mass, the slope or gradient needs to remain the same throughout the investigation.

Conclusion: the acceleration of the does not depend on the mass of the trolley and will remain fairly constant throughout.

Question 18

For practical investigating the effect of mass on the acceleration of a trolley, explain why it is better to use light gates and a data logger than a stopwatch to record time values.

Answer 18

More accurate readings can be taken with little or no human error and calculations can be performed quickly by the data logger to provide speeds and accelerations.

Question 19

For practical investigating effect of mass on the acceleration of a trolley, suggest how the investigation described above could be improved to obtain better results.

Answer 19

More accurate mass, more accurate gradient, reduce friction, more readings for mass, repeat readings to determine the precision.