Force

What is Force?

Force is defined as a push or pull on an object resulting from its interaction with another object. In physics, force causes an object with mass to change its velocity. It is an external agent that can change an object’s state of rest or motion, and it has both magnitude and direction. The point of application is where the force is applied, and the direction is where it acts. The SI unit of force is Newton (N).

Effects of Force

In physics, motion is the change in position over time. Force can:

• Move a stationary object.
• Stop or slow a moving object.
• Accelerate a moving object.
• Change the direction of a moving object.
• Alter the shape and size of an object.

Formula for Force

The amount of force can be calculated using the formula:

Where:

m is the mass

a is the acceleration

This formula shows that force equals mass times acceleration. Force is measured in Newtons (N), which is also written as 

Calculating Acceleration

Acceleration (a) can be found using the formula:

Where:

v is the velocity

t is the time taken

Force in Terms of Velocity and Time

Using the acceleration formula, force can also be written as:

Momentum and Force

Momentum (p) is given by:

Thus, force can also be described as the rate of change of momentum:

Units of Force

• In the CGS system, force is measured in dynes.
• In the SI system, force is measured in Newtons (N).

Types of Force

Force is an influence that can change the motion or shape of an object. There are two main types of forces based on how they act:

• Contact Force
• Non-Contact Force

Contact Force

Contact forces occur when objects physically touch each other.

Examples:

• Muscular Force: Using the strength of animals like bullocks, horses, or camels for tasks.
• Mechanical Force: Applied through machines or tools.
• Frictional Force: Acts between surfaces in contact, opposing the motion of one surface over the other.

Non-Contact Force

Non-contact forces act over a distance without physical contact.

Examples:

• Gravitational Force: The attractive force exerted by the Earth, causing objects to fall toward it.
• Electrostatic Force: The force between charged objects.
• Magnetic Force: The force exerted by a magnet on other magnets or magnetic materials.

These forces act through space, influencing objects without direct contact. For instance, gravity pulls objects toward the Earth, and magnetic forces act between magnets even when they are not touching.

Solved Examples on Force

Here are a few examples that illustrate the calculation and application of force using the formula F=ma.

Example 1: Calculating Force

1. A car with a mass of 1000 kg accelerates at a rate of . What is the force exerted on the car?

Solution:

Given:

Mass, 
Acceleration,

Using the formula 

So, the force exerted on the car is 2000N.

Example 2: Determining Mass

2. A force of 50N is applied to an object, causing it to accelerate at . What is the mass of the object?

Solution:

Given:

Force, 
Acceleration,

Rearranging the formula 

F = ma to solve for mass m:

The mass of the object is 10kg.

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