Question

An object of mass ‘m’ is allowed to fall freely from point A as shown in the figure. Calculate the total mechanical energy of the object at: (1) Point A (2) Point B (3) Point C (4) State the law which is verified by your calculations in parts (1), (2) and (3).

Answer 1

(1) 

At point A, 

Mechanical energy means K.E. + P.E. 

At height h above ground K.E. = 0 [ ∵ body is at real] 

P.E. = mgh 

KE + P.E. = 0 + mgh = mgh 

Total mechanical energy = mgh …….(i)

K.E. mgh 

K.E.+ P.E.mgh + O = mgh 

(4) The law which is verified in parts (I), (ii) and (iii) is conservation of energy i.e., total energy remains conserved. 

It may change from one form to another.