Question

A stone of mass 500 g is dropped from the top of a tower of 100 m height simultaneously other stone of mass 1 kg is thrown horizontally with a speed of 10 m/s from same point. The height of centre of mass of the above two stone system after 3 sec is : (g = 10 m/s²)

• A. 45 m
• B. 35 m
• C. 55 m
• D. None of these

Answer 1

Answer: (C)

55 m

Answer 2

If height of stones is h₁ and h₂ after t = 3 sec then,

h₁ = 100 – $\frac{1}{2}$gt² = 55 m

h₂ = 100 – $\frac{1}{2}$gt² = 55 m

\ h_CM =$\frac{m_{1}h_{1} + m_{2}h_{2}}{m_{1} + m_{2}}$= 55 m