An object has a mass of 15 kg and is accelerating to the right at 16.3 m/s2. the free-body diagram shows the horizontal forces acting on the object. what is the frictional force, ff, acting on the object? 5.5 n 15 n 244.5 n 494.5 n answer : 5.5 n

Refer to the free body diagram shown melow.

F =  applied force
R =  frictional force
m = 15 kg, the mass of the object

The acceleration (to the right) is 16.3 m/s², therefore
F - R = (15 kg)*(16.3 m/s²) = 244.5 N

The normal reaction is
N = mg = (15 kg)*(9.8 m/s²)  = 147 N
The frictional force is
R = μN = 147μ N,  where μ =  coefficient of kinetic friction.

Let us check possible answers:
If R = 5.5 N, then μ = 5.5/147 = 0.0374 (very likely)
If R = 15 N, then μ = 15/147 = 0.102 (possible)
If R = 244.5 N,   (Highly unlikely, exceed mg)
If R = 494.5 N, (highly unlikely, exceeds mg)

The most reasonable answer is R = 5.5 N