A rock is thrown straight up, with an initial velocity of 20 meters per second and from an initial height of 2 meters.

Question

The height h of the rock, in meters, after t seconds is described by the equation h(t)=2+20t-4.9t^2 .(calculator allowed) What is the rock’s average speed during the first two seconds of its flight? Include units.

Answer 1

The velocity of the rock is v(t)=20-9.8t (v is the derivative of h)

The peak of the path occurs at t=20/9.8.

v(0)=20 and v(2)=.4

[v(2)-v(0)]/2=-9.8 m/sec