Velocity-time curve for a body projected vertically upwards is

• parabola

• ellipse

• hyperbola

• straight line

D.

straight line

When the ball goes upwards the direction of velocity of the ball and the direction of acceleration of gravity are in the opposite directions of acceleration of gravity are in the opposite directions so the velocity of the ball decrease until it reaches the top and stops momentarily.

 v = u - gt          ... (i)

Then from the peak position, the ball will start to descend downwards due to the acceleration due to gravity that is g.

 v = -gt               ....(ii)

( negative sign is due to motion in downward direction)   

From both equations, the velocity and time are linearly proportional to each other which is the same as the equation of a straight line. So this graph will be a straight line starting from initial velocity (u) on the y-axis and slope g with time as the x-axis.