Question

A ball A is dropped from a building of height 45 m. Simultaneously another identical ball B is thrown up with a speed 50 m $s^{-1}$. The relative speed of ball B w.r.t. ball A at any instant of time is (Take g = 10 m $s^{-2}$).

• A. 0
• B. 10 m $s^{-1}$
• C. 25 m $s^{-1}$
• D. 50 m $s^{-1}$

Answer 1

The correct option is D 50 m $s^{-1}$

At anytime $t,$

$V_A=0-gt$ [Taking upward direction as $+ve.$]

$V_B=50-gt$

$V_{B|A}=50-gt-(-gt)=50m/s$