Question

1. a constant eastward horizontal force of 70 newtons is applied to a 20 kilogram crate moving toward the east on a level floor. if the frictional force on the crate has a magnitude of 10 newtons, what is the magnitude of the crates acceleration?

Explanation:

Step1: Calculate net - force

The applied force $F_{app}=70N$ (east - ward) and the frictional force $F_f = 10N$ (opposite to the motion, so west - ward). The net force $F_{net}$ is given by $F_{net}=F_{app}-F_f$.
$F_{net}=70 - 10=60N$ (east - ward)

Step2: Use Newton's second law

Newton's second law is $F_{net}=ma$, where $m = 20kg$ and $F_{net}=60N$. We want to find the acceleration $a$. Rearranging the formula for $a$ gives $a=\frac{F_{net}}{m}$.
$a=\frac{60}{20}=3m/s^{2}$

Answer:

$3m/s^{2}$