<span>The medium in which it travels through</span>
        
             
        
        
        
Years of research have demonstrated that rats are intelligent creatures who experience pain and pleasure, care about one another, are able to read the emotions of others, and would assist other rats, even at their own expense.
<h3>Experiments:</h3>
In trials carried out at Brown University in the 1950s, rats were trained to press a lever for food, but they stopped pressing the lever when they noticed that with each press, a rat in an adjacent cage would scream in pain (after experiencing an electric shock).
Rats were trained to press a lever to lower a block that was hanging from a hoist by electric shocks administered by experimenters. A rat was subsequently hoisted into a harness by the experimenters, and according to their notes, "This animal normally shrieked and wriggled sufficiently while dangling, and if it did not, it was jabbed with a sharp pencil until it exhibited indications of discomfort." Even if it wasn't in danger of receiving a shock, a rat watching the scenario from the floor would pull a lever to lower the hapless rodent to safety.
Learn more about experiments on rats here:
brainly.com/question/13625715
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Answer:
As the sound approaches, it gets louder (simply because you're closer to the source), and has a higher pitch. Then, as it passes, the sound suddenly dips down, and as it drives away you hear a lower pitch, plus a decreasing volume as the engine gets farther and farther away. 
Explanation:
 
        
             
        
        
        
Answer:
(1) 2.25m/s^2
(2) 45.6m
Explanation:
(1) A car accelerates uniformly from 12m/s to 39m/s in 12 seconds
Therefore the average acceleration can be calculated as follows
a = 39-12/12
a = 27/12
a= 2.25m/s^2
(2) A butterfly is flying at 4m/s , it accelerates uniformly at 1.2 m/s for 6 seconds 
u= 4
a= 1.2
t= 6
Therefore the distance can be calculated as follows
S= ut + 1/2at^2
= 4×6 + 1/2 × 1.2 × 6^2
= 24 + 1/2 × 1.2 × 36
= 24 + 1/2 × 43.2
= 24 + 21.6
S = 45.6m
Hence the butterfly travels at 45.6m