1.Easy
A 1 kg ball is dropped from rest from a height of 16 m. Ignore air resistance. Find its kinetic energy Ek just before it hits the ground.
m = 1 kgh = 16 mg = 9.81 m/s²
Ek = J
Work & energy worksheet with answers
2.Easy
A 4 kg ball is dropped from rest from a height of 37 m. Ignore air resistance. Find its speed v just before it hits the ground.
m = 4 kgh = 37 mg = 9.81 m/s²
v = m/s
3.Medium
A block slides from rest down a slope at 40° to the horizontal. The coefficient of kinetic friction is 0.15. Find its speed v after it has slid 5 m along the slope.
θ = 40°μ = 0.15d = 5 mg = 9.81 m/s²
v = m/s
4.Medium
A car travelling at 50 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 = 50 km/hμ = 0.6g = 9.81 m/s²
d = m
5.Hard
A 10 kg block is released from rest at height 4 m on a smooth ramp. At the bottom it crosses a rough horizontal strip 4 m long (μ = 0.3) and then runs onto a spring (k = 4000 N/m) on a smooth surface. Find the speed v of the block when it reaches the spring.
m = 10 kgh = 4 mL = 4 mμ = 0.3k = 4000 N/mg = 9.81 m/s²
v = m/s
6.Hard
A spring of stiffness 2000 N/m at the bottom of a 20° slope is compressed by 15 cm against a 3 kg block and released. The coefficient of kinetic friction between block and slope is 0.3. How far d up the slope does the block travel from the release point before it stops? (Ignore the short distance over which the spring pushes, i.e. take friction and gravity over the whole distance d.)
m = 3 kgk = 2000 N/mx = 15 cmθ = 20°μ = 0.3g = 9.81 m/s²
d = m
Answer key
- 1. Ek = 157 J
- 2. v = 26.94 m/s
- 3. v = 7.196 m/s
- 4. d = 16.39 m
- 5. v = 7.412 m/s
- 6. d = 1.225 m
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