Determine the applied force required to accelerate a 2.25 kg object rightward with a constant acceleration of 1.50 m/s2 if the force of friction opposing the motion is 18.2 N.
(Neglect air resistance.)

Explanation:

Im going to be using the rules for significant digits properly so I hope you're quite familiar with them. The equation we need for this is

F - f = ma where F is the applied force (our unknown), f is the frictional force, m is the mass, and a is the acceleration. Filling in:

F - 18.2 = 2.25(1.50) and

F = 2.25(1.50) + 18.2  Do the multiplication first and round to get

F = 3.38 + 18.2   The addition rules tell us that we will be rounding to the tenths place after we add to get

F = 21.6 N