Energy 5.2 Flashcards
What is wasted energy?
When something loses motion. E.g. when Jamal kicks a ball and it eventually stops rolling.
What energy is transformed or transferred when you kick a ball?
Chemical (from food you eat) –> kinetic, sound, and heat when you kick the ball.
Are cars more efficient than bikes?
No, because only 25% of the chemicals in the petrol go towards the car actually moving and the rest of the energy is wasted, whether the bike uses 95% of the energy used which makes it efficient.
What does energy efficiency measure?
It measures how much energy is converted into useful forms in a device.
What is the definition of renewable energy?
Energy that is unlimited in supply, and can be used over and over again. E.g. Solar panels, or wind turbines.
What is the definition of a non - renewable source?
A source that is limited in supply and can only be used once. E.g. Fossil fuels, because when it is burnt, you can’t use it again.
How do you calculate energy efficiency?
Useful energy output
——————————— x 100
Energy input
What are some ways to save energy in your house?
Floor insulation
Solar panels
Rain water tank
3A rated toilet and showerhead
Well ventilated refrigeration space
High quality pool blanket
Native vegetation
Light coloured roof (for insulation)
Eaves over windows (for shading)
Fluorescent lights/globes etc.
What is the process of change in energy when a ball is dropped?
Gravitational potential energy –> kinetic
–> Heat + sound.
What are risks that might make the bouncing ball prac less precise?
- Not starting on the exact height
- Something on the ground might skew
the result - Not calculating the rebound height
correctly
How do you calculate the efficiency of the rebound height of the balls?
Average rebound height of the ball
————————————————— x100
Starting height of the drop
