The force on an object due to gravity

Click for solutions

√

•Radiation from the sun passes through the Earth’s atmosphere, warming its surface.

•The warm surface then re-radiates lower frequency radiation back into the atmosphere.

•This is absorbed by greenhouse gases and the Earth warms up

The force on an object due to gravity

Click for solutions

√√√

√

Uranium or plutonium (fission fuels)

Doesn’t release carbon dioxide

Coal, oil or gas (fossil fuels)

Releases carbon dioxide when burnt

The force on an object due to gravity

Click for solutions

√√√

√

Plants obtained energy from the Sun by photosynthesis. Herbivores ate the plants, while carnivores ate the herbivores. The dead plants and animals were buried and after being subjected to high temperatures and pressures they were changed into fossil fuels.

The force on an object due to gravity

Click for solutions

√√√

√

work done = force x distance = 400 x 3 = 1200 J

power = work done / time = 1200 / 6 = 200 W

The force on an object due to gravity

Click for solutions

√ √√

√

For every 100 J supplied to the power station only 45 J of electricity is produced

chemical

electrical

Once installed there is no cost – sunlight is free

Photocells don’t produce any pollutants such as carbon dioxide

The force on an object due to gravity

Click for solutions

√ √√

√

KE = ½ mv2

*mass must be in kg*

= ½ (0.004) (302)

= 1.8 J

The force on an object due to gravity

Click for solutions

√ √√

√

work done = force x distance

distance = work done / force

distance = 1.8 / 45

= 0.04 m

work done = energy lost = 1.8 J

The force on an object due to gravity

Click for solutions

√ √

√

KE = ½ mv2

= ½ (85) (82)

= 2,720 J

GPE = initial KE – energy lost

= 2,720 – 1020

= 1,700

mgh = 1,700

85 x 10 x h = 1,700

850 h = 1,700

h = 2 m