In physics, mv - mu represents the change in momentum of an object.
Here's a breakdown:
- m: represents the mass of the object (typically measured in kilograms, kg).
- v: represents the final velocity of the object (typically measured in meters per second, m/s).
- u: represents the initial velocity of the object (typically measured in meters per second, m/s).
- mv: represents the final momentum of the object. Momentum is a vector quantity, defined as the product of an object's mass and its velocity.
- mu: represents the initial momentum of the object.
Therefore, mv - mu calculates the difference between the final and initial momentum, which is the change in momentum (also known as the impulse if this change is caused by a force acting over a time interval).
In simpler terms:
Imagine a ball rolling.
- mu is how much "oomph" the ball has before something happens (e.g., you kick it).
- mv is how much "oomph" the ball has after something happens.
- mv - mu is the change in the ball's "oomph". This change is caused by an external force.
Formula:
Δp = mv - mu
Where:
- Δp represents the change in momentum.
Example:
A 2 kg ball is initially moving at 3 m/s (u = 3 m/s). After being hit, its velocity changes to 7 m/s (v = 7 m/s) in the same direction.
- Initial momentum (mu) = 2 kg * 3 m/s = 6 kg m/s
- Final momentum (mv) = 2 kg * 7 m/s = 14 kg m/s
- Change in momentum (mv - mu) = 14 kg m/s - 6 kg m/s = 8 kg m/s
Therefore, the change in momentum of the ball is 8 kg m/s.
