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## Homework Statement

A ball (considered as a point) of mass m = 1.5kg is launched from a spring with a Δx= 5cm. Find the elastic constant K knowing that the ball is forced to travel the path ABC and that at point C its speed is zero. AB has no friction while BC has a friction μ

_{k}=0.05.

At point C the ball falls downwards with an air resistance of B = 0.5 N*s/m. What is the weight measured by a scale at point E? What is the distance EF?

This is the drawing

http://imageshack.us/a/img191/1360/55sp.jpg [Broken]

**Relevant equations**

E

_{0}W

_{nc}= E

_{f}

F

_{f}= -βv

## The Attempt at a Solution

I'm not sure how to actually solve this problem, I'm not sure about the process.

I assumed that at A there's an elastic potential energy, at B gravitational potential energy + kinematic energy and at C all the energy has been "consumed" by the work done by the force of friction since the speed is 0.

So I tried to set something like this

1/2kx

^{2}+ W

_{f}= mgh + 1/2mv

^{2}

Is this correct? At this point I would solve for K but I don't have the speed for v

^{2[/SUP. Plus where is the kinematic energy? Where does it start? Also I don't understand if to find K I must consider the all ABC path or AB is sufficient. Can you also help find out how to solve the other parts with air resistance and that curved path at the end? Even if you don't wanna give the answer at least knowing the equations to use and laws behind them.}

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