Answer :
Answer:
Explanation:
Potential energy lost by mass = mgh
= 10 x 9.8 x 2 = 196 J
a ) If v be velocity of mass at the bottom , its kinetic energy will be stored in spring as elastic energy
= 1/2 m v² = 1/2 k x² , k is spring constant , x is compression , m is mass falling down
.5 x 10 v² = .5 x 500 x .75²
v = 5.3 m /s
b ) kinetic energy of mass at the bottom
= /2 m v²
= .5 x 10 x 5.3²
= 140.45 J
energy lost by mass while coming down
=potential energy at the top - kinetic energy at bottom
= 196 - 140.45
= 55.55 J .
This is equal to negative work done by friction
work done by friction = - 55.55 J
c ) Since there will be no loss of energy in compression and extension of spring so , no loss of kinetic energy will take place of mass . So it wil have same velocity that is 5.3 m /s while on its return journey.
d ) kinetic energy at the bottom = 140.45
loss of energy by friction again
= 140.45 - 55.55
= 84.9 J
If h be the height attained
mgh = 84.9
10 x 9.8 x h = 84.9
h = .866 m
( We have assumed that loss of energy in return journey will be same due to friction . )