Two train cars moving in the same direction are going to be coupled together. The mass of the first car is 5,000 kg and is moving at 5 m/s; the second car weighs the same, but is moving at 1 m/s. How fast will the two coupled cars move and how much kinetic energy does the system lose from coupling the cars together after they collide

Explanation:

Given

Mass of the first car

Mass of the second car

The velocity of the first car is

The velocity of the second car is

Conserving momentum, take as the velocity after coupling

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.