Difference Between Balanced and Unbalanced Forces with Practical Examples
Avogadro’s number is a fundamental constant in chemistry and physics. It represents the number of individual units (such as atoms, molecules, or ions) in one mole of any substance. This value allows scientists to relate macroscopic measurements (grams, liters) to the actual number of particles at the atomic or molecular scale. Understanding Avogadro’s number is critical for quantifying substances, calculating reactions, and connecting laboratory results to theoretical models.
What is Avogadro’s Number?
Avogadro’s number is the fixed number of particles present in exactly one mole of a substance. Its accepted value is:
Avogadro’s Number (NA) = 6.022 × 1023
This means one mole always contains 6.022 × 1023 discrete particles, whether they are atoms in an element or molecules in a compound.
Units and Application of Avogadro’s Number
Avogadro’s number is dimensionless; it is simply a count. It connects the atomic scale (atoms or molecules) to the macroscopic unit of “mole.” The concept is widely used in stoichiometry, chemical equations, and molecular calculations.
- For atoms (e.g., 1 mol of carbon): 6.022 × 1023 atoms
- For molecules (e.g., 1 mol of O2): 6.022 × 1023 molecules
- For ions (e.g., 1 mol Na+): 6.022 × 1023 ions
Key Formulas Using Avogadro’s Number
| Formula | Purpose | Example Use |
|---|---|---|
| Number of particles = Moles × Avogadro’s number N = n × NA |
Calculate total atoms/molecules/ions in a sample | How many molecules in 2 mol H2O? |
| Moles = Given particles ÷ Avogadro’s number n = N ÷ NA |
Find molar amount from actual number of particles | How many mol are 1.2044 × 1024 atoms? |
Step-by-Step: Solving Problems with Avogadro’s Number
- Identify what you know (moles, mass, or number of particles).
- If starting with moles, multiply by Avogadro’s number to get the number of particles.
- If starting with particles, divide by Avogadro’s number to find moles.
Representative Example
Suppose you have 3 mol of oxygen molecules. To calculate how many molecules this corresponds to:
Number of molecules = 3 × 6.022 × 1023 = 1.8066 × 1024 molecules.
Summary Table: Avogadro’s Number at a Glance
| Parameter | Avogadro’s Number Value |
|---|---|
| Standard Value | 6.022 × 1023 units/mol |
| Unit | Dimensionless (pure number) |
| Applies To | Atoms, molecules, ions, electrons, etc. |
| Fundamental Role | Connects microscopic and macroscopic quantities |
Explore Further on Vedantu
- Forces – Meaning, Types, and Principles
- Equilibrium – Physics Concepts Explained
- Kinematics Equations – Motion and Mole Concept Applications
For in-depth content on the mole concept, particle counting, and practice questions, explore Vedantu’s Physics and Chemistry resources.
FAQs on Balanced Force in Physics: Meaning, Examples & Applications
1. What is a balanced force with example?
A balanced force occurs when equal and opposite forces act on an object, resulting in zero net force.
Example: A book resting on a table. Gravity pulls the book downward, and the table provides an equal upward force. The book remains stationary because the forces are balanced.
2. What are balanced and unbalanced forces phenomena?
Balanced forces keep an object at rest or moving at constant velocity, as the net force is zero.
Unbalanced forces cause a change in the state of motion, resulting in acceleration or deceleration.
Summary:
• Balanced: No net force, no change in motion
• Unbalanced: Net force present, motion changes
3. What happens if forces are balanced?
If forces acting on an object are balanced, there is no change in its motion.
• The object remains at rest if it was at rest.
• The object continues moving at the same speed and in the same direction if it was already in motion.
This concept is described by Newton's First Law of Motion (Law of Inertia).
4. Is balanced force always zero?
Yes, the net or resultant force in a balanced force situation is always zero.
• All forces cancel each other exactly.
• No acceleration occurs in the object.
Balanced force means total force = 0N.
5. What are 5 examples of balanced forces?
Five common examples of balanced forces are:
1. A hanging picture frame (tension equals weight)
2. A book lying on a table (gravity balanced by normal force)
3. A car moving at a constant speed on a straight road (engine force balances friction)
4. An object floating on water (upthrust equals weight)
5. Two people pushing a box from opposite sides with equal force (box remains still)
6. What is the difference between balanced and unbalanced force?
Balanced forces have a net force of zero, causing no change in motion. Unbalanced forces have a net force other than zero, resulting in acceleration.
• Balanced: No velocity change, object at rest or constant speed
• Unbalanced: Causes movement or change in speed/direction
• Exam Tip: Use free-body diagrams to identify if forces are balanced.
7. Do balanced forces change the shape of an object?
Yes, balanced forces can change the shape of an object if they act in opposite directions on different parts.
• Example: Pressing a rubber ball equally from opposite sides flattens it, even though the forces are balanced.
8. Are balanced and unbalanced forces related to Newton's Laws of Motion?
Yes, balanced and unbalanced forces are explained by Newton's Laws of Motion.
• Balanced forces: Newton's First Law (object remains in its state of motion unless acted upon by unbalanced force)
• Unbalanced forces: Newton's Second Law (F = ma, acceleration occurs when net force is not zero)
9. How can you identify balanced forces in a force diagram?
To identify balanced forces in a force diagram:
• Check that all force vectors acting on the object cancel each other.
• The sum of forces in each direction (x, y, and z) should be zero.
• If ΣF = 0 in every direction, forces are balanced.
10. Can an object be moving with balanced forces acting on it?
Yes, an object can move at constant speed if balanced forces act on it.
• Constant velocity means no acceleration
• Example: A car on a straight road at steady speed—engine force balances friction, so net force is zero
11. What are the effects of balanced force on an object?
The effects of balanced force are:
• No change in the object's state of rest or motion
• No acceleration occurs
• In certain cases, balanced forces can alter an object’s shape (e.g., compression from both sides)
12. Where do balanced forces occur in daily life?
Balanced forces are found in many daily situations, such as:
• A cup resting on a table
• A person standing still
• A tied tug-of-war rope when both teams pull equally
• Stationary elevators at a stop
In all these, the sum of all forces equals zero, creating equilibrium.
