Problem 7-35 Work-energy theorem - B

A girl pulls a box of mass $20.8\; kg$ across the floor. She is exerting a force on the box of $95.6\; N$, inclined at $35.0^\circ$ above the horizontal. The kinetic friction force on the box has a magnitude of $75.5\; N$. Use the work-energy theorem to determine the speed of the box after being dragged $0.750\; m$, assuming it starts from rest. [Ans. $0.45\; m/s$]

Accumulated Solution

Correct!
 
One of the following is incorrect; which one?

(A)   $\text{Work done = Change in}\; E_K$

(B)   $\sum F_d = \Delta ( ½ mv^2)$

(C)   $\sum F_d = \Delta E_K$

(D)   $\sum F_d = ½ m(v^2 - v_0{^2})$

(E)   $\sum F_d = ½ \;m(v - v_0)^2$