Question

a motor applies 300 n of force to a crate. the friction acting on the crate is 120 n, causing it to accelerate at 2.0 m/s^2. what is the mass of the crate? *

Explanation:

Step1: Calculate net - force

The net - force $F_{net}$ is the difference between the applied force $F_{applied}$ and the frictional force $F_{friction}$. So, $F_{net}=F_{applied}-F_{friction}$. Given $F_{applied} = 300\ N$ and $F_{friction}=120\ N$, then $F_{net}=300 - 120=180\ N$.

Step2: Use Newton's second - law

Newton's second - law is $F_{net}=ma$, where $m$ is the mass and $a$ is the acceleration. We know $F_{net}=180\ N$ and $a = 2.0\ m/s^{2}$. Rearranging the formula for $m$ gives $m=\frac{F_{net}}{a}$. Substituting the values, we have $m=\frac{180}{2}=90\ kg$.

Answer:

90 kg