Question

compare and contrast what relationship between an impules and a momentum change is.

Answer 1

Any moving object can have momentum. This is because momentum is mass in motion. The way we determine an object's momentum is fairly straightforward. Momentum is the object's mass times its velocity, or, in equation form, p=mv, where p is momentum, m is mass in kilograms, and v is velocity in meters per second. Momentum is proportional to both mass and velocity, meaning that a change in one will cause the same amount of change in the other. So if you increase an object's mass, you also increase its momentum. The same is true for velocity: increase or decrease the object's speed, and you increase or decrease its momentum by the same amount.

But usually it's the object's velocity that changes instead of its mass, right? You may remember that a change in velocity means the object is accelerating. You may also remember that acceleration is caused by a force and that the greater the force, the greater the acceleration. Therefore, the greater the acceleration, the greater the momentum!

Force is an important factor, but time also counts. Specifically, when we are interested in knowing how long the force acts. For example, if you push a box across the floor for just a few seconds, the time interval is very short. But if you push a box across the floor and you do so with the same force as before, but this time for several minutes, you've increased the amount of time the force acts. This longer time interval leads to a greater change in momentum. This change in momentum is called impulse, and it describes the quantity that we just saw: the force times the time interval it acts over. The greater the impulse, the greater the change in momentum. To change the impulse, you can either change the amount of force, or you can change the time interval in which that force acts. In equation form, we can write this relationship between impulse and momentum as:Ft=mv

The Greek letter delta means 'change in,' and we read this equation as force times the time interval equals change in mass times velocity. Be careful not to read this as 'force times time equals mass times velocity' because now you're saying that 'impulse equals momentum.' It's important to remember that impulse is a change in momentum, not momentum itself.