MHB Work energy principle and power

[Shah 72]

A box slides down a smooth ramp. The height of the ramp is 20cm and the length of the ramp is 2.5m. The box starts from rest. What is the speed of the box when it reaches the bottom of the ramp?
I don't understand how to solve this. Pls help

 

[I like Serena]

We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?

 

[Shah 72]

Increase in KE= loss of GPE
1/2mv^2= mgh
So gpe at the top = m×10× 0.2
GPE at the bottom = 0J

 

[Shah 72]

We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?

I don't understand how to solve this. Pls help

 

[I like Serena]

You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.

 

[Shah 72]

You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.

h=0.2m, so v= 2m/s. I was getting confused with the length of the ramp.
Thanks a lottt!