Question

A ball is rolled off the edge of a horizontal table at a speed of 4 m/second. It hits the ground after 0.4 second. Which statement given below is not true?

• A. it hits the ground at a horizontal distance 1.6 m from the edge of the table
• B. the speed with which it hits the ground is 0.4m/second
• C. height of the table is 0.8 m
• D. it hits the ground at an angle of $ 45{}^\circ $ to the horizontal

Answer 1

Answer: (B)

Given, Time after it hit the ground, $t =0.4 s$
Initial velocity in horizontal direction is $4 ms ^{-1}$
Initial velocity in vertical direction is $U _{ y }=0$
Acceleration in vertical direction, $a = g =10 ms ^{-2}$
Apply kinematic equation of motion
$ V = U +\text { at } $
$ V=0+10 \times 0.4=4 ms ^{-1} $
Hence, at $4 ms ^{1}$ ball will hit the ground.