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

AI Thread Summary
The discussion focuses on calculating the acceleration of a box subjected to a horizontal force and kinetic friction using Newton's Second Law. The net force is determined by subtracting the frictional force from the applied force, leading to the formula a = (F - f) / m. For the given values of a 412N force, 122N friction, and a 75kg mass, the calculation yields an acceleration of approximately 3.86 m/s². However, there is a debate about the accuracy of rounding the result to 4 m/s² without considering significant figures. The importance of precision in calculations is emphasized in the context of physics problems.
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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?
 
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well rounding because something is "close" is never correct how many sig. figs. do you have?
 
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