At a construction site a hoist performs two lifts without a pause between them

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

At a construction site a hoist performs two lifts without a pause between them. First, it raises a

400\,\text{kg}

pallet of bricks through

15\,\text{m}

20\,\text{s}

. Immediately afterwards, it raises a

600\,\text{kg}

pallet through

10\,\text{m}

25\,\text{s}

. Take

g = 9.8\,\text{m\,s}^{-2}

. (i) Compute the total mechanical work done by the hoist in the two lifts. (ii) Find the total time taken for both lifts. (iii) Calculate the average power output of the hoist over the entire operation and express your answer in horsepower

(1\,\text{hp}=746\,\text{W})

Related theory

Potential Energy
Power
Work, Energy and Power

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