Question

Block B has a 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 CD needed to hold the wedge from moving while B is sliding down A. Neglect friction

• A. $2\text{mg cos}\theta$
• B. $\frac{mg}{2}\text{cos}\theta$
• C. $\frac{mg}{2}\text{sin}2\theta$
• D. $\text{mg sin}2\theta$

Answer 1

The correct option is C $\frac{mg}{2}\text{sin}2\theta$

$T=\text{N sin}\theta$ and $N=\text{mg cos}\theta$
$T=\text{mg cos}\theta \text{sin}\theta =\frac{mg}{2}\text{sin}2\theta$