Question

Two blocks are kept in contact as shown in the figure.

Find the value of normal force exerted by the vertical wall on $20kg$ block. (Assume all surfaces are smooth)

$(\text{Take}g=10{\text{m/s}}^2)$

• A. $200N$
• B. $100N$
• C. $25N$
• D. $75N$

Answer 1

The correct option is D $75N$

FBD of $10\text{kg}$ block

$N_1=10g=100\text{N}$ ... (1)
$N_2=100\text{N}$ ... (2)

FBD of $20\text{kg}$ block

$N_2=50\sin {30}^{\circ }+N_3$
$\therefore N_3=N_2-50\sin {30}^{\circ }=100-25=75\text{N}$ ... (3)