Howard J. answered • 10/10/19
Tutor
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Principal Mech Engr with 35+ years' on-the-job physics experience
a ball is thrown straight downward with a speed of 0.5 meters per second from a height of 4 meters. what is the speed of the ball 0.7 seconds after it is released?
Let H(t)=height at time t
v(t)=speed at time t
v(t)=v(0)-gt
We know v(0) = -0.5 m/sec so
v(0.7) = -0.5-9.81(0.7) = -7 m/sec
Note the height is irrelevant and the solution is expressed to one significant figure (since the limiting number of significant figures from the problem statement is one).
