4-9 Force/mass - Newton's Second Law question

[Ant29]

Homework Statement

When a horizontal force F is applied to a box having a mass m, the box sides on a level floor, opposed by a force of kinetic friction f.

a. What magnitude of acceleration occurs for the box?
b. Calculate the acceleration if the horizontal force is 412N, friction is 122N, and the mass of the box is 75kg

Homework Equations

It's asking for acceleration, so I am choosing a=Fnet/m for the formula. Now, the problem has a force and friction

F - horizontal force 412N
m - mass 75kg
f - kinetic friction 122N
a - ?

a=F-f/m

The Attempt at a Solution

a = 412N - 122N/75 kg
a = 290N/75 kg
a=3.86 I'm rounding the answer because it's close to four, so a is 4. Is this correct?

 

[harvellt]

well rounding because something is "close" is never correct how many sig. figs. do you have?

 

[tomcue]

I would like to clarify that the unit of force is Newtons (N) and the unit of mass is kilograms (kg). In your attempt at the solution, you have correctly used the formula a=Fnet/m, but you have not used the correct units for the values. The correct solution would be a = (412N - 122N)/75kg = 290N/75kg = 3.87 m/s^2. Therefore, the correct answer is a = 3.87 m/s^2, which is approximately equal to 4 m/s^2. It is important to use the correct units in scientific calculations to ensure accuracy.