# Kinematics question

• Oct 8th 2009, 03:27 PM
Caturdayz
Kinematics question
A ball is thrown straight upward with a speed v from a point h meters above the ground. Show that the time taken for the ball to strike the ground is (v/g)[1+sqrt(1+(2hg/v^2)]

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I honestly have no idea where to start, just an optional problem that the teacher intended to be difficult, but any help would be appreciated.

It appears to be a quadratic... ?
• Oct 8th 2009, 05:34 PM
mr fantastic
Quote:

Originally Posted by Caturdayz
A ball is thrown straight upward with a speed v from a point h meters above the ground. Show that the time taken for the ball to strike the ground is (v/g)[1+sqrt(1+(2hg/v^2)]

---

I honestly have no idea where to start, just an optional problem that the teacher intended to be difficult, but any help would be appreciated.

It appears to be a quadratic... ?

Take upwards direction as the positive:

Initial velocity = v
Displacement = -h
Acceleration = -g
Final velocity = ?

Substitute the above into an appropriate uniform acceleration formula and solve for final velocity.