Thread: Ball thrown upwards

A ball weighing .15kg is thrown upwards at a rate of 20m/s from a building 30m high. Neglecting air resistance, formulate a differential equation govering the ball's motion, solve it, and use the solution to determine the maximum height of the ball.

Originally Posted by HelloWorld2

A ball weighing .15kg is thrown upwards at a rate of 20m/s from a building 30m high. Neglecting air resistance, formulate a differential equation govering the ball's motion, solve it, and use the solution to determine the maximum height of the ball.

Motion up: subject to the boundary conditions that at t = 0, and . (SI units used).

Originally Posted by mr fantastic

Motion up: subject to the boundary conditions that at t = 0, and . (SI units used).

This treats the top of the building as x = 0; in reference to the ground we can put x = 30.

So we just find an explicit expression for velocity, then integrate it, and apply the fact that s(0)=30 for the contstant. Then plug in the t that makes v=0?

Originally Posted by HelloWorld2

So we just find an explicit expression for velocity, then integrate it, and apply the fact that s(0)=30 for the contstant. Then plug in the t that makes v=0?

Yes.