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