(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A projectile is launched straight upward at +63.0 m/s from a height of 85.0 m, at the edge of a sheer cliff. The projectile falls, just missing the cliff and hitting the ground below.

Maximum height = 202.5m

1) Find the time it takes to hit the ground at the base of the cliff.

2) Find its velocity at impact

2. Relevant equations

x_{f}=x_{i}+v_{i}t+1/2at^{2}

v_{f}=v_{i}+at

3. The attempt at a solution

For #1 I tried this:

x_{i}=202.5 x_{f}=0 a=-9.80 v_{i}=0

0=202.5+0+1/2(-9.8)t^{2}

-202.5=-4.9t^{2}

41.327=t^{2}

t=6.429

But that's not the right answer

For #2 I tried this: (It depends on the answer to #1)

V_{f}=0+(-9.8)(6.429)

V_{f}=-63.004

But that's wrong too since #1 is wrong. What did I do wrong in #1?

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# Homework Help: Velocity of 1-dimensional projectile

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