The 75% energy which does not do any useful work gets dissipated as thermal energy in gasoline engines.
Explanation:
The efficiency of any engine like gasoline engine is the ratio of work done in contrast to heat or energy provided.
Gasoline engines are internal combustion engine. The thermal efficiency is calculated of these engines.
work done or efficiency= 
or heat absorbed is divided by heat used in doing work
the friction and in other forms heat gets lost.
In gasoline engine about 65 to 75 % heat gets emitted without any useful work done. The heat gets lost in friction, air turbulence, noise and work input to turn on the engine. After the dissipation of heat in it only 25% is used up by vehicle having gasoline engines.
Answer:
B. An experiment that you don't change any variables.
A mountain lion should have wider bone rings because it has a higher metabolic rate, and thus a faster growth rate
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Descriptive studies are designed primarily to describe what is going on or what exists. Causal studies, which are also known as “experimental studies,” are designed to determine whether one or more variables causes or affects the value of other variables.