Newton’s second law

Definition

Newton's second law states that the force acting on an object is equal to the mass of that object times its acceleration (F = ma). This law explains how the velocity of an object changes when it is subjected to an external force.

5 Must Know Facts For Your Next Test

1. Newton's second law connects force, mass, and acceleration in a linear relationship.
2. The formula F = ma can be used to calculate any one of these variables if the other two are known.
3. In orbital mechanics, this law helps explain how planets and satellites accelerate due to gravitational forces.
4. The units for force, mass, and acceleration in the SI system are Newtons (N), kilograms (kg), and meters per second squared (m/s²) respectively.
5. This law implies that heavier objects require more force to achieve the same acceleration as lighter objects.

Review Questions

• What is the mathematical formula representing Newton’s second law?
• How does Newton's second law apply to the motion of planets in their orbits?
• If you know the mass and acceleration of an object, how would you calculate the force acting on it?

Related terms

Newton’s First Law: An object will remain at rest or in uniform motion unless acted upon by an external force.

Gravitational Force: The attractive force between two masses.

Acceleration: The rate of change of velocity of an object with respect to time.