Question

25 a ramp has a length of 4.0 m and a height of 1.5 m. if a man pushes a 40.0-n crate to the top of the ramp with a force of 60.0 n, what is the efficiency of the ramp? (3 marks)

Explanation:

Step1: Calculate useful work done

Useful work is work against gravity: $W_{useful} = F_{g} \times h$
$W_{useful} = 40.0\ \text{N} \times 1.5\ \text{m} = 60.0\ \text{J}$

Step2: Calculate total work input

Total work is applied force over ramp length: $W_{total} = F_{applied} \times L$
$W_{total} = 60.0\ \text{N} \times 4.0\ \text{m} = 240.0\ \text{J}$

Step3: Compute efficiency of the ramp

Efficiency is ratio of useful to total work: $\text{Efficiency} = \frac{W_{useful}}{W_{total}} \times 100\%$
$\text{Efficiency} = \frac{60.0\ \text{J}}{240.0\ \text{J}} \times 100\% = 25\%$

Answer:

25%