Question

Three point particles A, B and C are projected from same point with same speed at t = 0 as shown in figure.
For this situation select correct statement(s).

• A. All of them reach the ground at same time.
• B. All of them have same horizontal displacement when they reach the ground.
• C. All of them reach the ground with same speed.
• D. None

Answer 1

The correct option is C All of them reach the ground with same speed.

Vertical component of initial velocities are different $\Rightarrow$ reach the ground at different time.

When a body is projected from top of the building of height H,
from equations of motion,
$|\overrightarrow{v}{|}^2-|\overrightarrow{u}{|}^2=2\overrightarrow{g}.\overrightarrow{S}$
$|\overrightarrow{v}{|}^2-|\overrightarrow{u}{|}^2=2g.|\overrightarrow{S}|\cos \theta$
$|\overrightarrow{v}{|}^2-|\overrightarrow{u}{|}^2=2g.H$
$|\overrightarrow{v}|=\sqrt{|\overrightarrow{u}{|}^2+2g.H}$
Speed of the body when it reaches ground is same for all the bodies, irrespective of angle of projection.