1.Easy
A hoist lifts a 200 kg load at constant speed through a height of 6 m in 20 s. Find the average power P it delivers to the load, in W.
m = 200 kgh = 6 mt = 20 sg = 9.81 m/s²
P = W
Work & energy worksheet with answers
2.Easy
A 4 kg ball is dropped from rest from a height of 31 m. Ignore air resistance. Find its kinetic energy Ek just before it hits the ground.
m = 4 kgh = 31 mg = 9.81 m/s²
Ek = J
3.Medium
A toy launcher has a vertical spring of stiffness 1500 N/m. A 0.25 kg ball is placed on it and the spring is compressed by 8 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 = 0.25 kgk = 1500 N/mx = 8 cmg = 9.81 m/s²
h = m
4.Medium
A 1 kg ball hangs on a light string of length 0.8 m. It is pulled aside until the string makes 90° with the vertical and released from rest. Find the tension T in the string when the ball passes the lowest point.
m = 1 kgL = 0.8 mθ = 90°g = 9.81 m/s²
T = N
5.Hard
A 2 kg cart is released from rest at a height of 5.3 m on a smooth track that leads into a vertical circular loop of radius 1.5 m. Find the normal force N the track exerts on the cart at the top of the loop.
m = 2 kgh = 5.3 mR = 1.5 mg = 9.81 m/s²
N = N
6.Hard
A 5 kg cart is released from rest at a height of 6 m on a smooth track that leads into a vertical circular loop of radius 2 m. Find the speed v of the cart at the top of the loop.
m = 5 kgh = 6 mR = 2 mg = 9.81 m/s²
v = m/s
Answer key
- 1. P = 588.6 W
- 2. Ek = 1216 J
- 3. h = 1.957 m
- 4. T = 29.43 N
- 5. N = 40.55 N
- 6. v = 6.264 m/s
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