Choose the object and draw its forces
A force describes an interaction: a push, a pull, friction, or gravity. Choose the object you are studying, then show each force acting on it with an arrow. The arrow direction matters. For forces on the same line, choose a positive direction before combining their values.
A change in motion depends on the net force
Equal opposing forces give a net force of zero. The object can remain at rest or keep moving at constant velocity. A nonzero net force changes velocity: its speed, direction, or both. For constant mass, net force = mass × acceleration; more net force gives more acceleration when mass stays the same.
Check the direction and the units
Use kilograms for mass, newtons for force, and metres per second squared for acceleration. Acceleration points in the net-force direction, which need not be the direction the object is already moving. Proportional reasoning helps compare two cases: doubling mass halves acceleration when the net force stays fixed.
Worked example
A cart pulled in opposite directions
A 2 kg cart has a 6 N pull to the right and a 2 N opposing force to the left. Its vertical forces balance. Taking right as positive, the net horizontal force is 6 − 2 = 4 N. Its acceleration is 4 ÷ 2 = 2 m/s² to the right. This describes the change in velocity, not the cart’s current speed.