Hi

The following question i am having problem with:

A tennis ball is served horizontally from 2.5m above the ground at 30m/sec. The net is 12m away and 0.9m high.

a) Find its velocity (v) at any time t seconds

This is what i done:

a=-gj

find the integral to get velocity

v=c_1 i + (-gt+c_2)j

v=12.6i+(-9.8t+2.5)j

P.S