Two cars traveling in opposite directions at the same speed of 10 mph collide he
ID: 1773929 • Letter: T
Question
Two cars traveling in opposite directions at the same speed of 10 mph collide head-on. Immediately after the collision, the cars move together in the same direction as the first car but at 5 mph. Which of the following statements is correct?
(a) Kinetic energy is conserved in the collision because the sum of the speeds of the cars after the collision is equal to the speed of the cars before the collision.
(b) The first car is three times as heavy as the second car.
(c)The first car is twice as heavy as the second car.
(d)The second car is twice as heavy as the first car.
(e) None of the statements can be judged correct or incorrect because not enough information is given.
Explanation / Answer
(b) The first car is three times as heavy as the second car.
explanation:
Let m1 and m2 be the masses of the cars
from conservation of momentum
Pi = Pf
m1 u1 + m2 u2 = m1 v1 + m2 v2
As stated in the question that the final velocity of the system is 5 mph in the direction first car, so
10 m1 - 10 m2 = (m1 + m2) 5
2 m1 - 2 m2 = m1 + m2
m1 = 3 m2
Hence, (b) The first car is three times as heavy as the second car.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.