A force of 100N was used to kick a football of mass 0.8kg. Find the velocity with which the ball moves if it takes 0.8s to be kicked
-
A.
(32ms^{-1} ) -
B.
(50ms^{-1} ) -
C.
(64ms^{-1} ) -
D.
(100ms^{-1} )
Correct Answer: Option D
Explanation
From Newton’s second law:
( F = frac{mV – mµ}{t} )
Let the final velocity = V; and since the football is initially at rest, its initial vel µ = 0, M = 0.8kg
( t = 0.8s \
implies 100 = frac{0.8V – 0.8 times 0}{0.8} \
text{Therefore } V = frac{100 times 0.8}{0.8} = 100ms^{-1} )