1.Easy
A crate is pulled 7 m along a level floor by a rope that makes 50° with the horizontal. The tension in the rope is 200 N. Find the work W done by the rope on the crate.
F = 200 Nd = 7 mθ = 50°
W = J
Work & energy worksheet with answers
2.Easy
A 1 kg ball is dropped from rest from a height of 35 m. Ignore air resistance. Find its speed v just before it hits the ground.
m = 1 kgh = 35 mg = 9.81 m/s²
v = m/s
3.Medium
A car travelling at 80 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 0.5. Find the stopping distance d.
v = 80 km/hμ = 0.5g = 9.81 m/s²
d = m
4.Medium
A car travelling at 40 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 0.6. Find the stopping distance d.
v = 40 km/hμ = 0.6g = 9.81 m/s²
d = m
5.Hard
A 5 kg block starts from rest at the bottom of a 25° slope and is pulled up the slope by a constant force of 55 N parallel to the slope. The coefficient of kinetic friction is 0.15. Find the speed v of the block after it has moved 2 m up the slope.
m = 5 kgF = 55 Nθ = 25°μ = 0.15d = 2 mg = 9.81 m/s²
v = m/s
6.Hard
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 m long (μ = 0.15) and then runs onto a spring (k = 2500 N/m) on a smooth surface. Find the maximum compression x of the spring.
m = 10 kgh = 2 mL = 1 mμ = 0.15k = 2500 N/mg = 9.81 m/s²
x = cm
Answer key
- 1. W = 899.9 J
- 2. v = 26.2 m/s
- 3. d = 50.34 m
- 4. d = 10.49 m
- 5. v = 4.699 m/s
- 6. x = 38.1 cm
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