**Acceleration** is the rate of change of velocity of an object with respect to time. It’s is the net result of all forces acting on the object, as described by Newton’s Second Law. ^{}The **SI** unit for accelerate is metre per second squared **(m⋅s ^{−2}). **The vector of the net force acting on a body has the same direction as the vector of the body’s acceleration, and its magnitude is proportional to the magnitude of the accelerate, with the object’s mass as proportionality constant.

**EX: **When a car starts from zero velocity, in an inertial frame of reference and it travels in straight line at increasing speeds, it is accelerating in the direction of travel. The forward force of the car is called a **linear acceleration**, the reaction to which passengers in the car experience as a force pushing them back into their seats. When changing direction, this is called radial acceleration, the reaction to which passengers experience as a sideways force. If the speed of the car decreases, this is an acceleration in the opposite direction of the velocity of the vehicle, sometimes called **deceleration** or **Retrograde burning** in spacecraft.

**Problem 1: A toy car accelerates from 3m/s to 5m/s in 5 s. Find its acceleration?**

**Answer:**

Given: Initial Velocity u = 3m/s,

Final Velocity v = 5m/s,

Time taken t = 5s.