Event violates the law of conservation …

carsCollisionThe two toy cars have equal masses. The cars move towards each other at 0.5 m/s. They collide and bounce off each other at 1 m/s. This event violates the law of conservation of
a) mass
b) momentum
c) kinetic energy
d) potential energy
e) (b) and (c)
f) charge
g) all of these  

Solution. Posted on Saturday, April 11, 2015.

We have to check the law of conservation of momentum and kinetic energy. Let’s start with the law of conservation of kinetic energy. m1*Va^2/2+m2*Vb^2/2=m1*Ua^2/2+m2*Ub^2/2 where Va, Vb velocities of the cars before collision and Ua, Ub velocities of the cars after collision. All we need to do is plug in values of velocity and we will see that the event violates the law of conservation of kinetic energy. It is important to mention that the event does not violate the law of conservation of momentum in case of a one dimensional collision. Finally, the answer is (c).

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