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When the displacement of a spring is reduced to half its original value, and the spring constant remains unchanged, what happens to the spring's potential energy?
It decreases to 1/2 of its original value
It decreases to 1/4 of its original value
It increases to 2 times its original value
It remains unchanged
It decreases to 1/4 of its original value
The potential energy stored in a spring is directly proportional to the square of its displacement. When the displacement is halved, the energy becomes one-fourth of the original value due to the square relationship.
The potential energy stored in a spring is directly proportional to the square of its displacement. When the displacement is halved, the energy becomes one-fourth of the original value due to the square relationship.
Think of a rubber band: pulling it back twice as far requires four times the effort, so releasing it back to half that distance leaves you with only a quarter of the potential energy stored compared to the fully stretched state.
Square the shift: If displacement changes by a factor of n, energy changes by a factor of n2.
U=21тАЛkx2 тАФ Elastic potential energy of a spring
UтИЭx2 тАФ Relationship between energy and displacement
The elastic potential energy (U) stored in a spring is calculated using the formula U=21тАЛkx2, where k is the spring constant and x is the displacement from the equilibrium position. Since UтИЭx2, if the new displacement xтА▓=2xтАЛ, then the new potential energy UтА▓=21тАЛk(2xтАЛ)2=21тАЛk(4x2тАЛ)=41тАЛU.
Potential energy is a scalar quantity.
The spring constant k depends on the material and geometry of the spring.
The displacement x is measured from the natural, unstretched position.
Useful for calculating work done in spring-mass systems.
Critical for understanding simple harmonic motion (SHM).
Mechanical watch movements
Vehicle suspension systems
The SI unit for potential energy is Joule (J).
Option A is incorrect because it ignores the quadratic dependency on displacement.
Option C is incorrect as it assumes a linear inverse relationship rather than a square.
Option D is incorrect as potential energy changes whenever the state of the spring changes.
B is correct тАФ Because the potential energy is proportional to the square of the displacement, halving the displacement results in a reduction to 1/4 of the original energy.
In any physics problem involving a 'square' relationship (like E=21тАЛmv2 or U=21тАЛkx2), always check the power of the variable before calculating the change.