The work done will be equal to the potential energy of the piano at the final position
P.E=m.g.h
.consider the plank the hypotenuse of the right triangle formed with the ground
.let x be the angle with the ground=31.6°
.h be the side opposite to the angle x (h is the final height of the piano)
.let L be the length of the plank
sinx=opposite side / hypotenuse
= h/L
then h=L.sinx=3.49×sin31.6°=0.638m
weight w=m.g
m=w/g=3858/10=385.8kg
Consider Gravity g=10m/s2
then P.E.=m.g.h=385.8kg×10×0.638=2461.404J
then Work W=P.E.=2451.404J
We will have the following:
Since it is a white rock, then when in a windowless room with just red light the color that will appear to our eyes is red. Since is the only color to reflect.
Answer:
Change in mechanical energy = work done by friction
so it is equal to

Explanation:
As we know that change in mechanical energy must be equal to the work done by non conservative forces only
So here when block moves down the inclined plane then the work done by friction force is given as

here we have

here we know that

so we have


Now the friction force on the block is given as



now work done by the friction is given as

