NECO 2003 Physics · Question 31

A machine has an efficiency of 80%. If the machine is required to overcome a load of 60N with a force of 40N, calculate its velocity ratio.

Options

A.0.53
B.0.83
C.1.20
D.1.50
E.1.88

Answer: E. 1.88

Explanation written with AI and checked against the answer key

Concept

For a simple machine:

Mechanical Advantage (MA) = Load ÷ Effort
Efficiency = (MA ÷ VR) × 100%

So VR = MA ÷ Efficiency.

Solution

MA = Load ÷ Effort = 60 ÷ 40 = 1.5
Efficiency = 80% = 0.80
VR = MA ÷ efficiency = 1.5 ÷ 0.80 = 1.875 ≈ 1.88

Check: Efficiency = 1.5 ÷ 1.875 = 0.80 = 80% ✓

Answer: E (1.88)

Tip: Students often stop at MA = 1.5 (option D). That is a trap. Remember that VR is always larger than MA for a real machine, because efficiency is below 100%. Use the chain: MA = Load/Effort, then VR = MA/efficiency.

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