Answer to Question #174792 in Physics for Nicole

Question

Students designed an experiment to determine how a force exerted on a system does work on that system as it moves through a displacement. In this case, the force is provided by the hanging mass m2 and the displacement is the vertical distance h indicated on the diagram. The mass of the string and the friction in the pulley are negligible, but there is a non-negligible force of friction Fk between m1 and the table. Assume that the system does move when released, and that the speed upon hitting the floor is v. Which of the following is a correct relationship between the quantities involved in the experiment?

(A) m2gh=12m1v2

(B) m2gh-Fkh=12m1v2

(C) m2gh-Fkh=12(m1+m2)v2

(D) m2gh=12(m1+m2)v2

Answer 1

From the energy principle:

$$m_2gh-F_kh=\frac{1}{2}(m_1+m_2)v^2$$

Answer: C