# Final velocity of the mass

## Homework Statement

A spring with a spring- constant 3.4N/ cm is compressed 29cm and released. The 2 kg mass skids down the frictional incline of height 50 cm and inclined at 21 degrees angle.
The acceleration of gravity is 9.8 m/s^2.
The path is frictionless except for a distance of .07 m along the incline which has a coefficient of friction of 0.5.

## Homework Equations

I am kind of completely lost.

## The Attempt at a Solution

so far this is what I have but its probably wrong anyway

50cos(21)= 46.67902132486
50sin(21)= 17.9183974

N=mg
N= (2)(9.8)= 19.6

Friction= NmK
Friction= (19.6)(0.5)= 9.8

PE= 14.297m
KE= 9.8

Total Energy= 24.097

Problem attached its #6..
Thanks

#### Attachments

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## Answers and Replies

Doc Al
Mentor
N=mg
N= (2)(9.8)= 19.6
The normal force while on the incline doesn't equal mg.

What's the total energy of the mass initially?

How much energy is dissipated due to work against friction as it slides down?

What's the final energy?

The normal force while on the incline doesn't equal mg.

What's the total energy of the mass initially?

How much energy is dissipated due to work against friction as it slides down?

What's the final energy?

So to get the normal force on an incline can I use the angle? Would it be like 9.8*cos(21)*2?
and how do you get friction for a specific area?

Doc Al
Mentor
So to get the normal force on an incline can I use the angle? Would it be like 9.8*cos(21)*2?
Yes.
and how do you get friction for a specific area?
Just like for anywhere else. Kinetic friction = μN.