Question

A body is dropped from the roof of a multi storeyed building. It passes the ceiling of the 15th storey at a speed of $20/m s^{-1}$ .If the height of each storey is 4m, the number of storeys In the building is (take $g = 1 0/ms^{-2}$ and neglect air resistance)

• A. 20
• B. 25
• C. 30
• D. 35

Answer 1

Answer: (A)

20

Answer 2

$\nu^2 - u^2 = 2a (nx)$ n = 5 + 15 = 20