Motion in a Straight Line - Result Question 43
45. If a ball is thrown vertically upwards with a velocity of $40 m / s$, then velocity of the ball after two seconds will be ( $g=10 m / s^{2}$ )
[1996]
(a) $15 m / s$
(b) $20 m / s$
(c) $25 m / s$
(d) $28 m / s$
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Answer:
Correct Answer: 45. (b)
Solution:
- (b) Initial velocity $(u)=40 m / s$ Acceleration $a=-g m / s^{2}=-10 m / s^{2}$
Time $=2$ seconds
By Ist equation of motion,
$v=u+a t$
$v=40-10(2)=20 m / s$
