$[11/12$ Points$]$

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A small block of mass m is place on top of a hill as shown in the figure at the right, a height h above a horizontal track. The hill is frictionless, but when the block reaches the horizontal track, there is a coefficient of friction, $.$ The block slides along the track for a distance $L$ and comes to a stop. For this motion air resistance can be ignored. We will take the origin of the coordinate system to be at $A,$ with $x$ being the horizontal coordinate with positive to the right, and $y$ being the vertical coordinate with positive up$.$ We will choose our system to include the block, the hill, the surface with friction, and the Earth. The parameters of the problem are those shown in the figure: $m,g,,d_1,L,d_2,h,$ and $.$ Also, the block has a speed $v_B$ at point $B$ at the bottom of the hill.

$1.$

A$.$ As the block slides from the top of the hill to point $B$ at the bottom of the hill, gravitational potential $vv$ energy is transformed into Are there any external forces that transfer energy in or out of the system as work? $q,?$

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B$.$ Use the parameters of the problem to write an expression for the known energy of the block at the top of the hill.

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C$.$ Use the parameters of the problem to write an expression for the known energy of the block at point B at the bottom of the hill.

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