Work Done

Aim

Aim: To investigate whether the work done pulling a mass up a ramp is equal to the energy gained by the mass, and whether the angle of the ramp changes either of these.

Equipment shown in the simulation

• Ramp with adjustable angle.
• Block of selectable mass.
• Rope from block over a pulley at the apex to a handle.
• Spring balance on the rope.
• Slope-distance scale (d).
• Vertical-height scale (h).

Part 1 — Effort with and without a ramp

1. Select 0.50 kg. Set angle to 60°. Read F.
2. Change the angle to 15°. What happens to F?
3. Try all four angles. What pattern do you notice? Is it easier or harder to pull the mass up a steep ramp?

Part 2 — Distance and height

1. Reset. Select 0.50 kg, 30°. Pull the handle so the slope scale reads 30 cm.
2. Read the height scale. How high has the block actually risen?
3. Repeat for slope distances 20 cm and 40 cm at the same angle. Record d and h each time.
4. What pattern do you notice between d and h at this angle?
5. Now change to 60°. Pull to slope = 30 cm. What does the height scale read now?
6. Write a sentence describing what happens to h when you make the ramp steeper for the same d.

Part 3 — Work done and energy gained

1. Reset. Select 0.50 kg, 30°. Pull to slope = 40 cm.
2. Record F, d, m, h.
3. Calculate F × d. Calculate m × g × h (g = 10 N/kg).
4. Compare. What do you notice?
5. Repeat at angles 15°, 45°, 60°, each time pulling so the block ends at the same vertical height (e.g. h = 20 cm).
6. Compare F × d and m × g × h across all rows.

Part 4 — What does the ramp let you do?

1. For the same final height, does F change with the angle? Does d change with the angle?
2. Does F × d change with the angle, or does it stay the same?
3. A ramp does not let you avoid doing work. What does it let you do instead?
4. Complete on your worksheet: Using a ramp lets you swap a large   for a small   over a longer   . The total   done is the same.

Part 5 — Stretch question

1. If the ramp were flat (θ = 0°), what would F have to be? What would happen to h?
2. If the ramp were vertical (θ = 90°), what would F equal? What would happen to d?
3. A removalist has a long ramp and a short ramp for loading a fridge into a van. Which should they choose, and why? Will they do less work either way?