Stored (potential) energy

Answer Key - Grade 8 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Ari lifts a 2 kg bag up a staircase, and it gains 120 J of stored energy. With g = 10 N/kg, how high was it lifted?

   6 m
2. 2.

   A 5 kg box is lifted onto a loading dock and gains 150 J of stored energy, Bo reads. With g = 10 N/kg, how high was it lifted?

   3 m
3. 3.

   A pulley raises a 3 kg bucket for Esme's tree house, giving it 240 J of stored energy. With g = 10 N/kg, how high was it lifted?

   8 m
4. 4.

   Jun moves a box to half the height, then adds a second identical box on top. How does the stored energy compare?

   • It doubles: the load is heavier
   • It is zero: the boxes are still
   • It is the same as before
   • It halves: height is what counts
5. 5.

   A 3 kg pot sits on a 2 m shelf and a 2 kg pot on a 3 m shelf. Which stores more energy, Kira?

   • The pot on the 3 m shelf
   • Neither, since both are still
   • They store the same
   • The 3 kg pot

6. Read this first

   Three objects on shelves (example data)

   object	mass (kg)	height (m)
   P	1	6
   Q	3	1
   R	2	4

7. 6.

   Luz's table lists three objects on shelves. Which stores the most energy from gravity?

   • They are the same
   • P, the highest one
   • Q, the heaviest one
   • R
8. 7.

   Milo says a book on a high shelf has no energy because it isn't moving. Agree or disagree?

   • Agree: energy needs motion
   • Disagree: it stores energy from its height
   • Disagree: books make heat
   • Agree: it gets energy once thrown
9. 8.

   Noah throws a ball straight up. A friend says it stores the most energy just as it leaves the hand, where it is fastest. Agree or disagree?

   • Disagree: nothing is stored while moving
   • Disagree: it stores the most at the top
   • Agree: the hand gives it stored energy
   • Agree: fastest means the most stored
10. 9.

    Pia holds a stretched band still and says it has energy only once it is let go. Agree or disagree?

    • Disagree: it stores sound energy
    • Disagree: it already stores elastic energy
    • Agree: it gets energy from moving
    • Agree: still things have no energy
11. 10.

    Zee lets a swing go and waits until it stops. What happened to the 300 J?

    • It turned back into the push
    • It became 300 J of thermal energy
    • It ran out and is gone
    • It is still stored in the swing