2.18 meh 9. How much kinetic energy in kg mph2 was lost during the collision? 2.
ID: 3281153 • Letter: 2
Question
2.18 meh 9. How much kinetic energy in kg mph2 was lost during the collision? 2. Two cars, one going east, the other south, have a "fender-bender" with each other, Each has a mass of 2000 kg. The speed of th unknown. When they crash, they do not stick together and there is little or no deformation. The first car is traveling at an angle of 25° south of east and the second car is traveling 15° south of east after the collision e car heading east registered on radar at 20 mph. The other car's speed is 10. What was the speed of the second car in mph just before the collision? 11. What was the speed of the first car in mph just after the collision? 12. What was the speed of the second car in mph just after the collision?Explanation / Answer
applying momentum conservation,
2000 x 20 i - 2000 v2i j = (2000)(v1f) (cos25i - sin25j) + 2000 v2f (cos15i - sin15)j
20i - v2i j = ( 0.906 v1f + 0.966 v2f)i - ( 0.423 v1f + 0.259 v2f)j
0.906 v1f + 0.966 v2f = 20
0.423 v1f + 0.259 v2f = v2i
Applying energy conservation,
2000 (20^2) /2 + 1000 v2i^2 = 1000 v1f^2 + 1000 v2f^2
v1f^2 + v2f^2 = v2i^2 + 400
v1f = 22.07 m/s
v2f = 0
v2i = 9.34 m/s
10. : 9.34 m/s
11. 22.07 m/s
12. 0
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