Aball is thrown vertically upward with a speed of 1.53 m/s from a point 4.21 m above the ground. calculate the time in which the ball will reach the ground.

The ball moves by uniformly accelerated motion, and its vertical position at time t is described by the following law

where
is the initial height from which the ball starts its motion
is the initial velocity of the ball
is the gravitational acceleration

The time in which the ball reaches the ground is the time t at which the vertical position y(t) becomes zero:

Which means


whose solutions are:


Neglecting the negative solution (since it has no physical meaning), we can say that the ball reaches the ground after 1.10 s.

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