- #1
rammer
- 23
- 0
Suppose we have a spring placed vertically on a table. We put a body with mass "m" on it. The spring compresses by "x".
Then sum of forces is zero, therefore:
kx=mg, so k=mg/x
But if we look on it as the energy problem, then: we hold the body on the string, then we release it, so loss of gravitational potential energy is "mgx" and gain of spring energy is 0.5*k*x^2.
From that:
k=2mg/x, which contradicts previous equation.
Where I did a mistake?
Then sum of forces is zero, therefore:
kx=mg, so k=mg/x
But if we look on it as the energy problem, then: we hold the body on the string, then we release it, so loss of gravitational potential energy is "mgx" and gain of spring energy is 0.5*k*x^2.
From that:
k=2mg/x, which contradicts previous equation.
Where I did a mistake?