Question

Pls solve fast mcq
A heavy weight is suspended from spring. A person raises the weight till it becomes slack. The work done by him is W . The energy stored in stretched spring was E . Gain in gravitational potential energy is
1)W
2)E
3)W+E
4)W-E
ONLY ANSWER IF U KNOW WITH PROPER EXPLAINATION

Answer 1

Gain in gravitational potential energy will be W + E.

• Work done by spring force is positive when a compressed spring is released or a stretched spring is released.
• Now, as per the principle of conservation of energy,

• W (mg) + W(man) + W(spring) = 0
• -ΔU + W + E = 0

Please note that ΔU is negative because work is done against the gravity.

• ∴ΔU = W + E