Answer:
- a) Mechanical advantage: 2.7
Explanation:
a. Mechanical advantage
The mechanical advantage of a system of pulleys is the ratio of the ouput force (weight of the object) to the input force (pulling force):
- Mechanical advantage = output force / input force
- Mechanical advantage = 330N/ 121N = 2.727 ≈ 2.7
b. Work input
Work is the product of the force applied by the distance traveled in the same direction:
- Work input = Input force × input distance = 121N × 16m = 1,936J
c. Work output
Using the law of conservation of energy, the work output is equal to the change in the potential energy of the block:
- ΔPotential energy = mass × g × height
- ΔPotential energy = weight × height = 330N × 3.6m = 1,188J
d. Efficiency
The efficiency is the ratio of the work output to the work input:
- Efficiency = Work input / Work output
- Efficiency = 1,188J / 1,936J = 0.61
You can check that the efficiency is also the ratio of the mechanical advantage to the ideal mechanical advantage
The ideal mechanical advantage is equal to the ratio of the input distance (pulling distance) to the output distance (lift distance):
- Ideal mechanical advantage = 16m/3.6m = 4.444
- Efficiency = mechanical advantage / ideal mechanical advantage
- Efficiency = 2.727 / 4.444 = 0.61
