Question

In the figure shown, all surfaces are smooth. Find net force on $6kg,4kgand10kg$ blocks.

• A. $18N,12N,30N$
• B. $60N$ on each block
• C. $12N,0N,0N$
• D. $100N,0N,-40N$

Answer 1

The correct option is A $18N,12N,30N$

The only forces acting on blocks are $100N$ and $40N$, all three blocks will be travelling with same acceleration.

$F_1-F_2=m_{total}a100-40=20a\Rightarrow a=3m/s^2$

The net forces on each block can be calculated using relation $F_{net}=ma$
$F_{net}A=m_A\times a=18N$
$F_{net}B=m_B\times a=12N$
$F_{net}B=m_C\times a=30N$