# Using Impulse to Solve For the Final Velocity

• spacestrudel
In summary: Got’cha! I don’t know, haha I was just taking the stuff he wrote on the board literally. Okay! So take the integral of the function given to then use to find the impulse ! Thank you.
spacestrudel
Homework Statement
What is the final velocity of a bullet given that its change in time is 0.1 seconds and F(t) = Fc(1+e^(-1the00t). The mass of the bullet is 20g.
Relevant Equations
Mvf - mvo = change in p = the integral of Fdt
Hi there,

Just asking a logistics question since I want to be sure I am approaching this problem correctly.

My professor showed me an example of a bullet being fired from a barrel, given its initial velocity was 0. The change in time was 0.1 seconds. The mass of the bullet is 0.02 kg. The equation he gave is F(t) = Fc(1+e(-100t)), where Fc = 100N.

Since we know that MVf - MV0 = Δp = ∫ Fdt, doesn't this mean I can set the given function equal to MVf, since it is already force as a function of time (also since we know the initial velocity equals zero)? Or am I missing something?

Only asking because I can't tell if it's just a ridiculously easy problem or I'm missing something.

spacestrudel said:
doesn't this mean I can set the given function equal to MVf
You mean the integral of the function, right?

spacestrudel
haruspex said:
You mean the integral of the function, right?
Does it still have to be the integral of that given function even though it is already in terms of F(t)? Because he said that the change in momentum was just the integral of F. So, since I have F(t) - isn't that technically the integral?

spacestrudel said:
Does it still have to be the integral of that given function even though it is already in terms of F(t)? Because he said that the change in momentum was just the integral of F. So, since I have F(t) - isn't that technically the integral?
No, what makes you think that? F(t) is the function, ∫F(t).dt is its integral. If F(t)=2t then its integral is t2+constant.

Delta2
haruspex said:
No, what makes you think that? F(t) is the function, ∫F(t).dt is its integral. If F(t)=2t then its integral is t2+constant.
Got’cha! I don’t know, haha I was just taking the stuff he wrote on the board literally. Okay! So take the integral of the function given to then use to find the impulse ! Thank you.

## 1. How is impulse related to final velocity?

Impulse is directly related to final velocity as it is defined as the change in momentum of an object. Final velocity is the velocity of an object after it has been acted upon by an external force, and the change in momentum is equal to the impulse applied to the object.

## 2. Can impulse be used to determine final velocity?

Yes, impulse can be used to solve for final velocity by using the equation Impulse = Change in Momentum = mass x (final velocity - initial velocity). By rearranging this equation, the final velocity can be solved for.

## 3. What are the units for impulse?

The units for impulse are typically expressed as Newton-seconds (N*s) or kilogram-meters per second (kg*m/s).

## 4. Is the final velocity always equal to the initial velocity plus the impulse?

No, the final velocity is not always equal to the initial velocity plus the impulse. This equation only holds true for situations where no other forces are acting on the object.

## 5. Can impulse be negative?

Yes, impulse can be negative. A negative impulse indicates that the force applied to the object is in the opposite direction of its initial velocity, causing the object to slow down or change direction.

Replies
19
Views
2K
Replies
1
Views
2K
Replies
10
Views
2K
Replies
8
Views
2K
Replies
14
Views
2K
Replies
7
Views
3K
Replies
1
Views
1K
Replies
5
Views
2K
Replies
5
Views
2K
Replies
9
Views
2K