# physics

posted by lee

If a ball is thrown upwards at 20 ft/sec, the height h after t seconds is given by h = -16t^2 + 20t.   How many seconds does it take for the ball to reach its maximum height, and what is this height?

1. bobpursley

at max height, Velocity is zero.

v=dh/dt=-32t+20=0 t= 20/32 seconds

calculate h at this time.

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