Question

A ball is dropped from a building of height40m simultaneously another ball is thrown up with a speed20m/s the relative speed of first ball w. r. t second ball at t=1 s is (g=10 m/s)

Answer 1

at t = 1s , velocity of ball thrown up

v₁ = 20 - 10(1) = 10m/s (upwards)

at t = 1s, velocity of ball dropped from building

v₂ = -10(1) = -10m/s (downwards)

Relative velocity⇒ v₁₂ = v₁ - v₂ = 20m/s