A10 kg box, sliding to the right across a rough horizontal floor, accelerates at -2 m/s^2 due to the force of friction. calculate the coefficient of kinetic friction between the box and the floor and the magnitude of the net force acting on the box.

According to Newton's second law of motion, Fnet = m x a. From the given above,
                                    Fnet = (10 kg) x (-2 m/s²) = -20 N
The force of friction, Ff, which is a negative force is the product of the normal force and the coefficient of friction,
                                       Ff = 20 N = k x (10 kg x 9.8 m/s²)
The value of k from the equation is 0.204. Thus, the coefficient of friction is equal to 0.204. 

systematic

Explanation:

Systematic error:

This type of error is the result of an improperly calibrated apparatus or and improperly designed experiment that introduces the same one directional bias into all of the measurements. A systematic error is an effect that changes all measurements by the same amount or by the same percentage. For example, a ruler that has a badly worn one end, will introduce the same amount of uncertainty (in this case systematic errors) is introduced to all measurements. Instrument zeroes should automatically be checked every time an instrument is used.

Random Error:

A random error is a result of fluctuations in experimental conditions (such as repetitive measurements) that cause a measured value to occur above or below the correct value with equal probability. For example, when we read the meter stick with naked eye in successive measurements, we may be unable to judge the position of the markings on the meter stick accurately enough to obtain repeatedly the same result. This results in fluctuations in the measured values. Sometimes, the fluctuations are intrinsic to the system under investigation (as in the radioactive source, where the number of the emerging radioactive particles arises from the basic nature of radioactive decay). These uncertainties (or errors) can be estimated by using statistical methods (average, standard deviation, mean, mode,). Note that there are other uncertainties, such as instrument uncertainty, which can be estimated by personal judgment. For example, the instrument uncertainty of a meter stick is usually 0.1 cm.