KVPY2020PhysicsMotion in One Dimension
Three balls, A , B and C , are released and all reach the point X (shonw in the figure). Balls A and B are released from two identical structures, one kept on the ground and the other at height, h , from the ground as shown in the figure. They take time t A and t B respectively to reach X (time starts after they leave the end of the horizontal portion of the structure). The ball C is released from a point at height,
Options
- At C < t A < t C
- Bta = tb = tc
- Ct C = t A < t C
- Dt B < t A = t C
Correct answer
B. ta = tb = tc
Step-by-step solution
Work done by gravity on A and B is same. ∴ Horizontal velocity of A = horizontal velocity of B as they leave the horizontal portion of the structure. ∴   t A = t B … ( i ) Also vertical velocity of A and vertical velocity of C when released are both zero ∴ They both will cover same vertical distance in same time. ∴   t A = t C . . . ( ii ) From ( i ) and ( ii ) t A = t B = t C Note : Correction in option option B should be t A = t B = t C