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## Homework Statement

A boy throws a rock off of a cliff that is 33m high. The rock weights 1 kilogram and it's inital velocity is 13.5m/s. It is thrown at an angle of 40° with the horizon.

Initial Velocity = 13.5m/s

mass = 1 kg

θ=40°

Δy = 33m

g = 9.81 m/s^2

## Homework Equations

Potential Energy (Joules) = Ug = mgy

Kinetic Energy (Joules) = K = .5(m)(v^2)

## The Attempt at a Solution

Calculate the velocity of the rock just before it hits the ground at bottom of cliff. No heat is generated--assume ideal conditions.

Potential Energy -> (Ug = mgy)

= (1kg)(9.81m/s^2)(33m)

= 323.4J

Kinetic Energy -> (K = .5(m)(v^2)

= .5(1kg)(13.5m/s^2)

= 91.125 J

This is where I get lost, I don't understand how to solve for the END velocity. I also didn't incorporate anything with the angle...I just feel lost and I would greatly appreciate assistance.