Question

Block $B$ has mass $m$ and is released from rest when it is on top of wedge $A$, which has a mass $3\, m$. Determine the tension in cord $C D$ needed to hold the wedge from moving while $B$ is sliding down $A$. Neglect friction.

• A. $2 m g \cos \theta$
• B. $\frac{m g}{2} \cos \theta$
• C. $\frac{m g}{2} \sin 2 \theta$
• D. $m g \sin 2 \theta$

Answer 1

Answer: (C)

$T=N \sin \theta$ and $N=m g \cos \theta$
$T=m g \cos \theta \sin \theta=\frac{m g}{2} \sin 2 \theta$