Newton’s second law may be the most intuitive for students.  The tutor offers some commentary.

In high school, Newton’s second law is probably the most used of the three, since it’s the one with a formula:

F_net=ma

where

F=force (in Newtons)
m=mass (in kg)
a=acceleraton (in m/s²)

Example: Neglecting friction, how much force is needed to accelerate a 1.5 tonne car at 1.7m/s² on a flat road?

Solution: Since we are to neglect friction, and the car is not fighting gravity, all the force we apply is net force. With the mass being 1.5 tonnes, we must convert it to 1500kg (1 tonne=1000kg). The acceleration is given as 1.7m/s². Plugging those values into the formula, we arrive at

F=1500*1.7=2550N=2600N (sig figures)

So, it takes 2600N of force to accelerate the 1.5 tonne car by 1.7m/s².

Net force means force that is not fighting any opposition. Notice that net force is only needed to acclerate an object; in the absence of friction or gravity, no force is needed to maintain constant velocity, be it 1m/s or 100km/h. Of course, we are touching on Newton’s first law now. In that context, net also means unbalanced.

By the way: this site has several articles on significant figures (aka significant digits). You can search them up in the field at top right.

Source:

Heath, Robert W. et al, Fundamentals of Physics. 1981: D.C. Heath Canada Ltd.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.