Honors Physics

Conservation of Energy

A 2 kg block slides a distance of 3.0m down a frictionless ramp angled at 30 degrees from the horizontial. The block's final kinetic energy is 35 J. Determine the following:
A) The initial kinetic energy
B) The initial velocity of the block

Step one - Draw a Picture

Find the Initial Potential Energy

First find the initial height $sin(\theta)=\frac{H}{Distance \ traveled\ down\ the\ Ramp}$


Now can find the initial potential energy

$PE_{i} = 2(9.81)(1.5)$
$PE_{i} = 29.4 J$

Starting with the idea of conservation of energy
we can find the initial kinetic energy
Note the final potential energy is 0 J since
the object is at the bottom of the ramp at a
height of 0 m.


Now we can solve for the initial velocity
of the block from $KE_i$