1.Easy
A 4 kg ball is dropped from rest from a height of 17 m. Ignore air resistance. Find its speed v just before it hits the ground.
m = 4 kgh = 17 mg = 9.81 m/s²
v = m/s
Work & energy worksheet with answers
2.Easy
A 1 kg ball is dropped from rest from a height of 26 m. Ignore air resistance. Find its kinetic energy Ek just before it hits the ground.
m = 1 kgh = 26 mg = 9.81 m/s²
Ek = J
3.Medium
A 1800 kg car drives up an 8° slope at a constant 54 km/h. Air resistance and rolling resistance together amount to 200 N. Find the power P the wheels must deliver, in kW.
m = 1800 kgθ = 8°Fr = 200 Nv = 54 km/hg = 9.81 m/s²
P = kW
4.Medium
A 5 kg ball hangs on a light string of length 1 m. It is pulled aside until the string makes 40° with the vertical and released from rest. Find the tension T in the string when the ball passes the lowest point.
m = 5 kgL = 1 mθ = 40°g = 9.81 m/s²
T = N
5.Hard
A 2.5 kg block is released from rest at height 2.5 m on a smooth ramp. At the bottom it crosses a rough horizontal strip 4 m long (μ = 0.25) and then runs onto a spring (k = 1500 N/m) on a smooth surface. Find the speed v of the block when it reaches the spring.
m = 2.5 kgh = 2.5 mL = 4 mμ = 0.25k = 1500 N/mg = 9.81 m/s²
v = m/s
6.Hard
A 15 kg block starts from rest at the bottom of a 30° slope and is pulled up the slope by a constant force of 135 N parallel to the slope. The coefficient of kinetic friction is 0.3. Find the speed v of the block after it has moved 4 m up the slope.
m = 15 kgF = 135 Nθ = 30°μ = 0.3d = 4 mg = 9.81 m/s²
v = m/s
Answer key
- 1. v = 18.26 m/s
- 2. Ek = 255.1 J
- 3. P = 39.86 kW
- 4. T = 72 N
- 5. v = 5.425 m/s
- 6. v = 3.517 m/s
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