The wise and careful use of energy is called CONSERVATION
A pump jack scaffold must be fitted with two positive gripping mechanisms to prevent slippage. Pump jacks are a uniquely designed scaffold consisting of a platform supported by movable brackets on vertical poles. The brackets are designed to be raised and lowered in a manner similar to an automobile jack. It is important to make sure that pump jack brackets have two positive gripping mechanisms to prevent any failure or slippage.
Work done = force x distance = 40 x 2 = 80 Joules.
Answer:
it holds the bone and helps to move
I don't know if this is right