Energy Efficiency

Efficiency is always _____________

• less than 1%

• more than 100%

• less than 100

• less than 100%

The energy output will always be ______________

• less than the energy input

• more than the energy input

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

If a cyclist puts 600 J of work on his bicycle and the bicycle gives out 140 J of useful work. Calculate the efficiency of a cyclist.

• { Work Output / Work Input } × 100 %

     = {140 x 600} × 100 %

     = 8400000 %

• { Work Output / Work Input } × 100 %

     = {140 / 600} × 100 %

     = 23.3 %

A heat engine gives out 500 J of heat energy as useful work. If the energy supplied has a value of 1250 J, what is the engine's efficiency?

• 40%

• 2.5 %

Tags

NGSS.HS-PS3-3

Efficiency is always less than 100%, why?

• It isn't, it should be equal to 100%

• Because of energy transference due to friction

Tags

NGSS.HS-PS3-4

How can we increase efficiency?

• Reduce the cold

• Get more the friction

• Drive slower

• Reduce the friction

Tags

NGSS.HS-ETS1-3

What is wasted energy?

• The energy that is lost to heat or other energy types that aren’t useful.

• A comparison of how much energy is used to do work versus how much is lost or wasted to the environment.

• The energy that you throw away.

• The total amount of energy put into a system.

Tags

NGSS.HS-PS3-4

What is useful energy?

• The total amount of energy put into a system.

• The energy that is lost to heat or other energy types that aren’t useful.

• The energy that is created or destroyed.

• The energy that is used to achieve the desired outcome or do work.

Tags

NGSS.HS-PS3-4

What is efficiency?

• The measurement of how fast someone runs.

• The ability to do work.

• The total amount of energy put into a system.

• A comparison of how much energy is used to do work versus how much is lost or wasted to the environment.

Tags

NGSS.HS-ETS1-3

If Tad runs up a flight of stairs with a height of 10 meters in 5 seconds and his twin brother (who has the same mass) runs up the same flight of stairs in 4 seconds. Who has more power?

• Tad

• Tad's twin brother