1. What Is Deceleration?
Deceleration is the process in which the velocity of an object decreases with time. It is also called negative acceleration.
Whenever an object slows down, it is said to be decelerating.
1.1. Deceleration as Negative Acceleration
Acceleration measures change in velocity. When this change reduces the speed, the acceleration value becomes negative. This is called deceleration.
1.2. Everyday Meaning
If you apply brakes on a bicycle or a car, the vehicle slows down. This slowing effect is deceleration.
2. Why Does Deceleration Happen?
Deceleration occurs when some force acts in the direction opposite to the motion. This could be due to brakes, friction, air resistance, or any force opposing motion.
2.1. Examples of Opposing Forces
- Brake pads apply force opposite to a car’s wheels.
- Friction between shoes and ground stops a running person.
- Air resistance slows down a fast-moving cyclist.
3. Formula for Deceleration
The same formula for acceleration is used to calculate deceleration:
\( a = \dfrac{v - u}{t} \)
If the final velocity \( v \) is less than the initial velocity \( u \), the value of \( a \) becomes negative. This indicates deceleration.
3.1. Example Calculation
If a scooter slows down from 20 m/s to 5 m/s in 3 seconds, then:
\( a = \dfrac{5 - 20}{3} = -5 \, \text{m/s}^2 \)
The negative sign shows the scooter is decelerating.
3.2. Units of Deceleration
The unit is the same as acceleration:
- meters per second squared (m/s²)
4. Types of Deceleration
Deceleration can happen in different ways depending on how the object slows down.
4.1. Uniform Deceleration
The object slows down at a constant rate. Example: A train applying steady brakes reduces its speed uniformly.
4.2. Non-Uniform Deceleration
The rate of slowing is not steady. Example: A car in traffic slows down quickly, then gently, then more quickly again.
5. Deceleration in Everyday Situations
Deceleration is very common in real life. Any time an object reduces its speed, it is undergoing deceleration.
5.1. Examples
- A football slowing down on grass due to friction.
- A cyclist stopping at a red light.
- A ball thrown upward slowing down due to gravity.
- A roller coaster slowing at the end of the ride.