1.Easy
A 10 kg ball is dropped from rest from a height of 27 m. Ignore air resistance. Find its speed v just before it hits the ground.
m = 10 kgh = 27 mg = 9.81 m/s²
v = m/s
Work & energy worksheet with answers
2.Easy
A hoist lifts a 250 kg load at constant speed through a height of 30 m in 10 s. Find the average power P it delivers to the load, in kW.
m = 250 kgh = 30 mt = 10 sg = 9.81 m/s²
P = kW
3.Medium
A toy launcher has a vertical spring of stiffness 200 N/m. A 0.5 kg ball is placed on it and the spring is compressed by 10 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 = 0.5 kgk = 200 N/mx = 10 cmg = 9.81 m/s²
h = m
4.Medium
A car travelling at 60 km/h on a level road brakes hard and skids to a stop with its wheels locked. The coefficient of kinetic friction between the tyres and the road is 0.8. Find the stopping distance d.
v = 60 km/hμ = 0.8g = 9.81 m/s²
d = m
5.Hard
A 2 kg cart is released from rest at a height of 20 m on a smooth track that leads into a vertical circular loop of radius 5 m. Find the normal force N the track exerts on the cart at the top of the loop.
m = 2 kgh = 20 mR = 5 mg = 9.81 m/s²
N = N
6.Hard
A 4 kg block rests on a rough horizontal table (μ = 0.2). 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 1.5 m.
m1 = 4 kgm2 = 4 kgμ = 0.2d = 1.5 mg = 9.81 m/s²
v = m/s
Answer key
- 1. v = 23.02 m/s
- 2. P = 7.357 kW
- 3. h = 0.2039 m
- 4. d = 17.7 m
- 5. N = 58.86 N
- 6. v = 3.431 m/s
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