Posted by Jeremy on Wednesday, June 6, 2012 at 1:50pm.
How fast would a 9g fly have to be traveling to slow a 1910kg car traveling at 61 mph by 6 mph if the fly hit the car in a totally inelastic headon collision?
Could someone explain the steps, please?

Physics  Jeremy, Wednesday, June 6, 2012 at 1:51pm
The answer is supposed to be 1.27e+06 mph, but I'm not sure how to solve for it.

Physics  MathMate, Wednesday, June 6, 2012 at 3:34pm
Use conservation of momentum for inelastic collisions (when both masses travel at the same final speed in the same direction):
m1u1+m2u2=(m1+m2)v
Here
m1=0.009 kg
u1=to be found
m2=1910 kg
u2=61 mph
(m1+m2)=1910.009
v2=55 mph
So
0.009u1+1910*61 = (1910.009)(55)
Solve for u1
u1=(1910.009*551910*61)/0.009
=1.27*10^{6} m/s
The negative sign means the fly travels in the opposite direction to the car. 
Physics  Edward, Wednesday, November 7, 2012 at 11:36pm
it wouldn't slow the car down at all its redundet there just isn't enough pressure behind the fly to stop the car or to slow it down it would kill the fly and make a speck of guts on the windshield