Question

Two workmen are employed on a building project

i) Workmen 1 drops hammer with force to the ground the hammer has a mass of 2kg and is dropped from a height of 4.8m above the ground

a) Calculate the change in gravitational potential energy of the hammer when at is dropped

b) Describe the energy changes from the time the hammer leaves the hand of workmen 1 until it is at rest on the ground

c) Workmen 2 picks up the hammer and takes it back up the ladder to workmen 1.He climbs the first 3.0m in 5.0s. His total weight, including the hammer is, 520N. Calculate the useful power which his legs are producing.

Class 9​

Answer 1

Answer:

a 94.08 b 312w

Explanation:

a p=mgh p=2×9.8×4.8=94.08 b power = work done /time w=fs=520×3(f=520 because weight is force apllied by earth) power=1560/5 =312

Answer 2

Answer:

The answer by the previous person is mostly ight but his bit c is wrong as

Explanation:when the workman takes the hammer back up it will reach its initial position and in such a case there will be no displacement which would lead to there being no 'useful' power