Question

Find the maximum force that should act on the $7\text{kg}$ body for the system to accelerate together with $1{\text{m/s}}^2$. Take $g=10{\text{m/s}}^2$.

• A. $15\text{N}$
• B. $20\text{N}$
• C. $30\text{N}$
• D. $50\text{N}$

Answer 1

The correct option is C $30\text{N}$

We know that by formula,

$F_{\text{max}}=(m_1+m_2)({\mu }_{1}g+a_s)$
$(m_1=7\text{kg};m_2=3\text{kg};{\mu }_1=0.2;{\mu }_2=0.3)$
$a_s=1{\text{m/s}}^2$
$=(3+7)(0.2\times 10+1)$
$=10\times 3=30\text{N}$