A man is sitting on a 20 m height building and his mass is 50 kg. Calculate the mechanical energy.

9810 Joules

Explanation:

Given parameters are,

m = 50 kg

h = 20m

the man is not moving, therefore, K. E = 0

The formula of mechanical energy

M.E = 1/2 mv2 + mgh

Since K.E is 0, the equation becomes,

M.E = mgh

M.E = 50 ×9.81 ×20

M.E = 9810 J

Hence the mechanical energy is 9810 Joules

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray