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Q.
Velocity-time curve for a body, projected vertically upwards, is:
BHUBHU 2004Motion in a Straight Line
Solution:
From equation of motion, we have
$v=u-g t$
Where $v$ is final velocity, $u$ is initial velocity, $g$ is acceleration due to gravity and $t$ is time.
Since, body is projected vertically upwards final velocity $u=0$. $\therefore u=g t$
This equation is form of straight line equation
$y=m x+c$
Hence, graph between velocity and time is a straight line.