Lesson: Chapter 18 — Work, Energy and Power

18.2. Potential energy 5 of 8 Reset answers

Clear all your answers?

This erases every answer in this set and starts you again at question one. Your score will be gone.

Type these four numbers to confirm:

Those numbers don't match. Look at them again and type them.

Yes, clear Keep them

Question 5

A fruit on a tree has a mass of 200 g and hangs 4 m above the ground. What is its gravitational potential energy? (g = 10 m s^-2)

A 8000 J B 0.8 J C 800 J D 8 J

The right answer is the one marked above.

8 J. 200 g is 0.2 kg, so E_p = 0.2 × 10 × 4 = 8 J.

8000 J is what you get by putting 200 into the formula. It is a thousand times too large, and nothing about the number itself looks obviously wrong — which is what makes the mistake worth guarding against.

Answer the question to continue.