Saving energy and energy exchange
Answers are for parents and teachers.
1
A 75 W appliance runs for 4 hours. How many W·h does it use?
300
2
300 g of water at 70 °C is mixed with 300 g at 30 °C. What is the final temperature in °C?
50
3
Write 3 rules for saving energy at home and discuss them with your family.
For example: switch off lights, unplug standby devices, use LED lamps.
4
Write an energy conversion chain: sunlight → plant → human muscles → movement.
Light energy → chemical energy in the plant → food → muscle energy → mechanical energy (movement).