The hardest part of the job is to find the right formula to use, and write it down. You've already done that ! The rest is just turning the crank until an answer falls out.
You wrote. E = m g h.
Beautiful.
Now divide each side by (g h), and you'll have the formula for mass:
m = E / (g h).
You know all the numbers on the right side. Just pluggum in, do the arithmetic, and you'll have the mass.
Answer: 12 N to the right
Explanation:
If we calculate the net force acting on the box, we will have:
<u>In y-component:</u>
(1)
Where 
is the Normal force, directed upwards and 
is the weight of the box (gravity force), directed downwards.
(2)
(3) Hence the net force in the vertical component is zero
<u>In x-component:</u>
(4)
Where 
and 
(5)
(6) This is the net force in the horizontal component
Therefore, the total net force acting on the box is 12 N directed to the right
From A to B its 5 ohm.
above shown 6 and 12 ohm resistors are in parallel to short circuit hence their equivalent resistance is zero.
(Current doesnt flow through a resisstor if there is a Short circuit alternate.
