A very strong, but inept, shot putter puts the shot straight up vertically with an initial velocity of 11.1 m/s. How long does he have to get out of the way if the shot was released at a height of 2.27 m, and he is 1.96 m tall?

Question

Physics

Gideon Frederick

2 December, 15:40

A very strong, but inept, shot putter puts the shot straight up vertically with an initial velocity of 11.1 m/s. How long does he have to get out of the way if the shot was released at a height of 2.27 m, and he is 1.96 m tall?

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Answers (1)

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Toby Davila · Answer 1

We need to use the kinematic equation

S=ut + (1/2) at^2

where

S=displacement (+=up, in metres)

u=initial velocity (m/s)

t=time (seconds)

a=acceleration (+=up, in m/s^2)

Substitute values

S=displacement = 1.96-2.27 = - 0.31 m (so that shot does not hit his head)

u=11.1

a=-9.81 (acceleration due to gravity)

-0.31=11.1t + (1/2) (-9.81) t^2

Rearrange and solve for t

-4.905t^2+11.1t-0.31=0

t=-0.02756 or t=2.291 seconds

Reject the negative root to give

t=2.29 seconds (to 3 significant figures)