From a lift moving upwards with a uniform acceleration a $$=$$ $$2$$ $$ms-2$$, a man throws a ball vertically upwards with a velocity v $$=$$ $$12$$ $$ms-1$$ relative to the lift. The ball comes back to the man after a time t. Find the value of t in seconds. Take $$g=10ms-2$$

Question

From a lift moving upwards with a uniform acceleration a $$=$$ $$2$$ $$ms-2$$, a man throws a ball vertically upwards with a velocity v $$=$$ $$12$$ $$ms-1$$ relative to the lift. The ball comes back to the man after a time t. Find the value of t in seconds. Take $$g=10ms-2$$

Infinity Learn · Accepted Answer

Taking upward direction as positive, let us work in the frame of lift. Acceleration of ball relative to lift = (g + a) downwards, So a_rel = -(g + a), initial velocity: u_rel = v, final velocity: v_rel = -v as the ball will reach the man with same speed w.r.t lift

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$v_{rel} = u_{rel} + a_{rel} t \Rightarrow - v = v + (- g - a) t \Rightarrow t = 2 s$

Relative velocity in 1-d

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From a lift moving upwards with a uniform acceleration a = 2 ms^-2, a man throws a ball vertically upwards with a velocity v = 12 ms^-1 relative to the lift. The ball comes back to the man after a time t. Find the value of t in seconds. Take $g = 10 m s^{- 2}$

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Relative velocity in 1-d

Remember concepts with our Masterclasses.

From a lift moving upwards with a uniform acceleration a = 2 ms-2, a man throws a ball vertically upwards with a velocity v = 12 ms-1 relative to the lift. The ball comes back to the man after a time t. Find the value of t in seconds. Take g=10ms-2

Ready to Test Your Skills?

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From a lift moving upwards with a uniform acceleration a = 2 ms^-2, a man throws a ball vertically upwards with a velocity v = 12 ms^-1 relative to the lift. The ball comes back to the man after a time t. Find the value of t in seconds. Take $g = 10 m s^{- 2}$