A small toy car with a mass of 0.4 kg and a velocity of 5 m/s crashes into another toy car that was at rest with the same mass. The first toy car stops moving and the second toy car then moves forward and crashes into the third toy car that was at rest with a mass of 0.2 kg. a) If the system is closed, what is the velocity of the third toy car?

b) Show how you calculated the velocity in the space below.
Will give you brainliest if answered correctly

Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. the researchers grew one type of bacteria in twenty-four identical covered petri dishes. then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. they left the remaining six petri dishes closed as a control group. when the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. the researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. which statement best explains why the researchers’ conclusion was not justified? the experiment tested too many variables. the control group was not treated the same as the experimental group. the sample size of twenty-four petri dishes is not large enough. the single type of bacteria is not adequate to make any conclusions.