Force Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Force.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

A push or pull interaction between two objects that can cause a change in an object's velocity (speed or direction), described as a vector quantity measured in newtons.

Anything that makes something move, stop, speed up, slow down, or change direction.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Force is an interaction between objects that changes motion.

Common stuck point: Force isn't the same as motion—an object can have forces on it and still not move (if forces balance).

Sense of Study hint: When solving a force problem, first draw a free-body diagram showing all forces on the object. Then resolve each force into components along your chosen axes. Finally, apply Newton's second law (F_{\text{net}} = ma) separately for each axis to find unknown forces or acceleration.

Worked Examples

Example 1

easy
A 5 \text{ kg} box is pushed across a floor with a force of 20 \text{ N}. If there is no friction, what is the acceleration of the box?

Solution

  1. 1
    Identify the given values: mass m = 5 \text{ kg}, applied force F = 20 \text{ N}, and no friction.
  2. 2
    Apply Newton's second law: F = ma
  3. 3
    Solve for acceleration: a = \frac{F}{m} = \frac{20}{5} = 4 \text{ m/s}^2

Answer

a = 4 \text{ m/s}^2
Force is a push or pull that causes a change in an object's motion. When a net force acts on an object, it accelerates according to Newton's second law F = ma.

Example 2

medium
Two forces act on an object: F_1 = 15 \text{ N} to the right and F_2 = 8 \text{ N} to the left. What is the net force on the object?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
A force of 12 \text{ N} acts on a 3 \text{ kg} object. What acceleration does the object experience?

Example 2

medium
A 2.5 \text{ kg} drone speeds up from 4 \text{ m/s} to 10 \text{ m/s} in 3 \text{ s} while flying straight. What net force acts on the drone?
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Background Knowledge

These ideas may be useful before you work through the harder examples.

accelerationmass