1. Change in Speed:
* Acceleration: This is the most common cause of a change in velocity. Acceleration is the rate of change of velocity over time. If an object speeds up, it has positive acceleration; if it slows down, it has negative acceleration (also called deceleration).
* Forces: Forces are the primary cause of acceleration. Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).
2. Change in Direction:
* Turning: Even if an object maintains a constant speed, it can change its velocity by changing direction. For example, a car traveling at a constant speed on a roundabout is constantly changing its velocity due to the continuous change in direction.
* Curvature of path: When an object moves along a curved path, even if its speed is constant, its velocity is changing because its direction is changing.
Examples:
* A car accelerating from rest to 60 mph.
* A ball thrown straight up in the air, slowing down as it goes up and speeding up as it comes down.
* A car turning a corner at a constant speed.
* A satellite orbiting the Earth at a constant speed.
In summary:
* Acceleration (due to forces) causes a change in speed.
* Changing direction (even at constant speed) causes a change in velocity.
It's important to remember that both a change in speed and a change in direction result in a change in velocity.
