Work & energy worksheet with answers

Free printable Work & energy worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
500 kgh = 21 mt = 20 s

A hoist lifts a 500 kg load at constant speed through a height of 21 m in 20 s. Find the average power P it delivers to the load, in kW.

m = 500 kgh = 21 mt = 20 sg = 9.81 m/s²
P = kW
2.Easy
m = 10 kggh = 14 m

A 10 kg ball is dropped from rest from a height of 14 m. Ignore air resistance. Find its kinetic energy Ek just before it hits the ground.

m = 10 kgh = 14 mg = 9.81 m/s²
Ek = J
3.Medium
25°d = 10 mμ = 0.3

A block slides from rest down a slope at 25° to the horizontal. The coefficient of kinetic friction is 0.3. Find its speed v after it has slid 10 m along the slope.

θ = 25°μ = 0.3d = 10 mg = 9.81 m/s²
v = m/s
4.Medium
0.05 kgk = 1500 N/mh = ?

A toy launcher has a vertical spring of stiffness 1500 N/m. A 0.05 kg ball is placed on it and the spring is compressed by 4 cm, then released. Ignoring air resistance and the spring’s mass, find the height h the ball rises, measured from its position when the spring was compressed.

m = 0.05 kgk = 1500 N/mx = 4 cmg = 9.81 m/s²
h = m
5.Hard
h = 2 mL = 1.5 mμ = 0.3k = 2500 N/m

A 10 kg block is released from rest at height 2 m on a smooth ramp. At the bottom it crosses a rough horizontal strip 1.5 m long (μ = 0.3) and then runs onto a spring (k = 2500 N/m) on a smooth surface. Find the speed v of the block when it reaches the spring.

m = 10 kgh = 2 mL = 1.5 mμ = 0.3k = 2500 N/mg = 9.81 m/s²
v = m/s
6.Hard
5 kg4 kgμ = 0.15d = 2 m

A 5 kg block rests on a rough horizontal table (μ = 0.15). A light string runs from it over a smooth pulley at the edge of the table to a hanging 4 kg block. The system is released from rest. Find the speed v of the blocks after the hanging block has dropped 2 m.

m1 = 5 kgm2 = 4 kgμ = 0.15d = 2 mg = 9.81 m/s²
v = m/s

Answer key

  1. 1. P = 5.15 kW
  2. 2. Ek = 1373 J
  3. 3. v = 5.438 m/s
  4. 4. h = 2.446 m
  5. 5. v = 5.515 m/s
  6. 6. v = 3.764 m/s

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