# Forces and Motion: Velocity and Acceleration

## Forces and Motion: Velocity and Acceleration

- Velocity: Velocity is a vector quantity, which means it has both magnitude (speed) and direction. It is often described as the speed in a given direction.
- Measuring Velocity: Velocity can be calculated using the formula v = s/t, where ‘v’ is velocity, ‘s’ is displacement (distance moved in a specific direction) and ‘t’ is time.
- Uniform Velocity: When an object’s velocity remains constant, it is said to have uniform velocity. In this case, the object covers equal distances in equal time intervals.
- Acceleration: Acceleration is a measure of how rapidly an object’s velocity is changing. It is a vector quantity, meaning it also has both magnitude and direction.
- Measuring Acceleration: Acceleration can be calculated using the formula a = (v-u)/t, where ‘a’ is acceleration, ‘v’ is final velocity, ‘u’ is initial velocity and ‘t’ is time taken.
- Positive Acceleration: Positive acceleration indicates an increase in velocity. When an object is speeding up, it is accelerating.
- Negative Acceleration: Negative acceleration, also referred to as deceleration, signifies a reduction in velocity. When an object is slowing down, it is decelerating.
- Non-uniform Acceleration: If the rate of change of velocity is not constant, the object is said to be experiencing non-uniform acceleration.
- Graphical Representation: Velocity-time graphs can depict motion. Uniform velocity is represented by a horizontal, straight line while a sloped line indicates acceleration or deceleration. The rate of acceleration or deceleration corresponds to the steepness of the slope.
- Acceleration due to Gravity: When an object is in freefall, it accelerates due to gravity. This acceleration is approximately 9.8 m/s^2 towards the Earth’s centre.
- Finally, the second law of motion explains how force, mass, and acceleration are related. It states that the force applied on an object is equal to the mass of the object multiplied by its acceleration (F = ma). This relationship shows that if a force is applied on an object, it will accelerate.