Potential Energy Practice

Sample questions

5 of 8 — sign in to practice the rest with adaptive difficulty and mastery tracking.

1. Sample 1difficulty 1/5

   For an object of fixed mass on Earth's surface, gravitational PE plotted vs height is a straight line. The slope of this line equals

   • A

     $m$

   • B

     $1/(m g)$

   • C

     $m g$

     check_circle
   • D

     $g$

   Why

   $U_g = m g h$ → slope $= m g$.

   View full solution & statsarrow_forward

2. Sample 2difficulty 1/5

   A spring with constant $k = 200~\text{N/m}$ is compressed $0.10~\text{m}$. How much elastic potential energy is stored?

   • A

     $20~\text{J}$

   • B

     $2.0~\text{J}$

   • C

     $0.5~\text{J}$

   • D

     $1.0~\text{J}$

     check_circle

   Why

   $U_s = \tfrac{1}{2} k x^2 = \tfrac{1}{2}(200)(0.10)^2 = 1.0~\text{J}$.

   View full solution & statsarrow_forward

3. Sample 3difficulty 1/5

   A spring with $k = 400~\text{N/m}$ is compressed $0.05~\text{m}$. The stored elastic PE is

   • A

     $10~\text{J}$

   • B

     $0.50~\text{J}$

     check_circle
   • C

     $0.20~\text{J}$

   • D

     $1.0~\text{J}$

   Why

   $U_s = \tfrac{1}{2}k x^2 = \tfrac{1}{2}(400)(0.0025) = 0.50~\text{J}$.

   View full solution & statsarrow_forward

4. Sample 4difficulty 2/5

   A spring stretched $0.10~\text{m}$ stores $2.0~\text{J}$. To store $8.0~\text{J}$ in the same spring, by how much should it be stretched?

   • A

     $0.28~\text{m}$

   • B

     $0.20~\text{m}$

     check_circle
   • C

     $0.40~\text{m}$

   • D

     $0.80~\text{m}$

   Why

   $U \propto x^2$. $U$ quadrupling means $x$ doubles → $0.20~\text{m}$.

   View full solution & statsarrow_forward

5. Sample 5difficulty 2/5

   Stretching a spring $0.20~\text{m}$ from natural length stores $4.0~\text{J}$. The spring constant is

   • A

     $200~\text{N/m}$

     check_circle
   • B

     $100~\text{N/m}$

   • C

     $50~\text{N/m}$

   • D

     $400~\text{N/m}$

   Why

   $U = \tfrac{1}{2}k x^2 \Rightarrow k = 2U/x^2 = 8/0.04 = 200~\text{N/m}$.

   View full solution & statsarrow_forward