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- Homework Statement
- Two children are playing a game in which they try to hit a small box on the floor with a marble fired from a spring-loaded gun that is mounted on a table. The target box is 2.20 m horizontally from the edge of the table. Bobby compresses the spring 1.10 cm, but the marble falls 27.0 cm short. How far should Rhoda compress the spring to score a hit?

- Relevant Equations
- U(x) = (1/2)kx^2

KE = (1/2)mv^2

K

1/2)kx

1/2)kx^2 = F∆d.

The solution says that I should just substitute v as d/t. But could anyone explain why my reasoning is wrong? Thanks.

_{i}+ U_{i}= K_{f}+ U_{f}1/2)kx

^{2}= (1/2)mv_{f}^{2}, but W = (1/2)mv_{f}^{2}= F∆d, so1/2)kx^2 = F∆d.

The solution says that I should just substitute v as d/t. But could anyone explain why my reasoning is wrong? Thanks.