Question

A 1,240-kg car traveling initially with a speed of 25.0 m/s in an easterly direction crashes into the rear end of a 8,700-kg truck moving in the same direction at 20.0 m/s (see figure below). The velocity of the car right after the collision is 18.0 m/s to the east.

Two images depicting a before and after scenario of a car colliding with the back of a truck.

• Before: The car is moving at a velocity of +25.0 m/s. This is shown as a rightward-moving horizontal arrow above the car. The truck is moving at a velocity of +20.0 m/s. This is shown as a rightward-moving horizontal arrow, shorter than that of the car, above the truck.
• After: The car is shown crashing into the back of the truck. At this point, the velocity of the car is shown to be +18.0 m/s. This is shown as a rightward-moving horizontal arrow above the car. The velocity of the truck is shown to be v. This is shown as a rightward-moving horizontal arrow, longer than that of the car, above the truck.

(a) What is the velocity of the truck right after the collision? (Round your answer to at least three decimal places.)
m/s (east)

(b) How much mechanical energy is lost in the collision?
______ J

(C) Account for this loss in energy. Explain.

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Answer 1

c. The mechanical energy in collisions of macroscopic objects like car, truck etc is converted to vibrational energy of atoms which results in deformation of bodies and heating effect.