Question

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 crate’s acceleration?

Answer 1

`3 m/s^2`

Step-by-step explanation:

Newton's second law states that:

`\sum F = ma`

where

`\sum F` is the resultant of the forces acting on an object

m is the mass of the object

a is the acceleration

In this case we have two forces:

F = +70 N (east direction) is the horizontal push

Ff = -10 N (west direction) is the frictional force

so the net force is

`\sum F=70 N - 10 N = 60 N`

We also know the mass of the crate

m = 20 kg

So we can find the acceleration

`a=(sum F)/(m)=(60 N)/(20 kg)=3 m/s^2`