- #1
matadorqk
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Homework Statement
Before a collision, a 25-kg object is moving at +12m/s. Find the impulse that acted on teh object if, after the collision, it moves at:
a. 8.0m/s
b.-8.0m/s
Homework Equations
(c)=changes in:
To find impulse, we would use the F=ma, so F=m*(c)v/(c)t
So, F(c)t = m(c)v
Therefore, F(c)t=p2-p1 (impulse-momentum theorem).
The Attempt at a Solution
Ok, so here's what I did. Let's solve A first.
GIVEN:
m=25kg
v1=12m/s
v2=8m/s
F=25*(8.0-12)/(c)t
F= -100/(c)t
So, we take the difference in time to the other side.
F(c)t=-100
Therefore, its impulse is -100. At first I got confused because I had left two variables, but I think that's the impulse because F(c)t=p2-p1, so:
p2-p1=-100
25(8)-(25)(12)=-100
-100=-100
Im assuming that's the impulse, so its -100 N*s.
So, let's do this for B, which is -8.
GIVEN:
m=25kg
v1=12m/s
v2=-8.0m/s
F=?
F(c)t=m(v2-v1)
Impulse=25(-8-12)
Impulse=25(-20)
Impulse=-500
Seems to make sense, because to make the object that's moving go on its opposite direction it must be really strong. And also, both answers are negative as it moves in the opposite direction.
I would appreciate if you could check over my work to see if it is correct.