When cars are equipped with flexible bumpers, they will bounce off each other du

Question

When cars are equipped with flexible bumpers, they will bounce off each other during low-speed collisions, thus causing less damage. In one such accident, a 1800 kg car traveling to the right at 1.60 m/s collides with a 1450 kg car going to the left at 1.10 m/s . Measurements show that the heavier car's speed just after the collision was 0.270 m/s in its original direction. You can ignore any road friction during the collision.

Part A

What was the speed of the lighter car just after the collision?

m/s

Part B

Calculate the change in the combined kinetic energy of the two-car system during this collision.

J

Explanation / Answer

Part-A
m1u1 + m2u2 = m1v1 + m2v2
given, m1= 1800kg; u1 = 1.60 m/s; m2 = 1450kg; u2 = -1.10 m/s; v1 = 0.270 m/s; v2 = ?
{m1u1 + m2u2 - m1v1} / m2 = v2
v2 = 799 / 1450 m/s = 0.5510 m/s to the right.
Part-B
K.E. (before Collision) = 1/2 m1u12 + 1/2 m2u22 = 2304 + 877.25 = 3181.25 J
K.E. (after Collision) = 1/2 m1v12 + 1/2 m2v22 = 65.61 + 220.11= 285.72 J
Change in K.E. = K.E. (after Collision) - K.E. (before Collision) = 285.72 - 3181.25 J = - 2895.53 J

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.