Asked by Emily
How fast would a 9-g fly have to be traveling to slow a 1790-kg car traveling at 58 mph by 4 mph if the fly hit the car in a totally inelastic head-on collision?
Answers
Answered by
Tim Korenman
Then the car's initial velocity is -50 mph.
The collision is totally inelastic, so the final velocity of both fly and car is -44 mph.
Total initial momentum = (4/1000)u - 1980*50 = 0.004u - 99000 kg mph.
Total final momentum = (1980 + 4/1000)*(-44) = -87120.176 kg mph.
Momentum is conserved, so 0.004u - 99000 = -87120.176.
ˆ 0.004u = 99000 - 87120.176 = 11879.824.
ˆ u = 11879.824/0.004 = 2969956 mph.
So the fly's velocity would have to be 2,969,956 mph. That's almost 825 miles per second!
Just plug in your numbers and chug away.
The collision is totally inelastic, so the final velocity of both fly and car is -44 mph.
Total initial momentum = (4/1000)u - 1980*50 = 0.004u - 99000 kg mph.
Total final momentum = (1980 + 4/1000)*(-44) = -87120.176 kg mph.
Momentum is conserved, so 0.004u - 99000 = -87120.176.
ˆ 0.004u = 99000 - 87120.176 = 11879.824.
ˆ u = 11879.824/0.004 = 2969956 mph.
So the fly's velocity would have to be 2,969,956 mph. That's almost 825 miles per second!
Just plug in your numbers and chug away.
Answered by
Emily
How are you getting -44 mph for the final velocity?