Question

A ball is rolled off the edge of a horizontal table at a speed of $4m/second$. It hits the ground after $0.4second$. Which statement given below is true

• A. It hits the ground at a horizontal distance $1.6m$ from the edge of the table
• B. The speed with which it hits the ground is $4.0m/second$
• C. Height of the table is $0.8m$
• D. It hits of the ground at an angle of ${60}^o$ to the horizontal

Answer 1

The correct option is B The speed with which it hits the ground is $4.0m/second$

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

$V=U+at$

$V=0+10\times 0.4=4m{s}^{-1}$

Hence, at $4m{s}^1$ ball will hit the ground.