Out of the choices given, igniting the gas-air mixture supplies the heat for the hot reservoir in a car's engine. The correct answer is C.
Answer:

Explanation:
As we know by radioactivity law

so here we will have


now we will have


now we also know that



All fluids exert pressure like the air inside a tire. The particles of fluids are constantly moving in all directions at random. As the particles move, they keep bumping into each other and into anything else in their path. These collisions cause pressure, and the pressure is exerted equally in all directions.
The step of this scientific method is "draw conclusion".
<h3>What is scientific method?</h3>
The scientific method is the process of objectively establishing facts through testing and experimentation.
The basic scientific process or scientific method involves the following;
- making an observation
- forming a hypothesis
- making a prediction
- conducting an experiment
- analyzing the results and
- drawing conclusion.
Thus, if Kim’s experiment showed that chicken eggshells were stronger when she gave the hen feed, to which extra calcium had been added. The step of this scientific method is "draw conclusion".
Learn more about scientific method here: brainly.com/question/17216882
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Answer:
1) The greatest height attained by the ball equals 20.387 meters.
2) The time it takes for the ball to reach 15 meters approximately equals 1 second.
Explanation:
The greatest height will be attained when the ball stop's in the air and starts falling back to the earth.
thus using third equation of kinematics we obtain the height attained as

where
'v' is the final speed of the ball
'u' is the initial speed of the ball
'a' is the acceleration that the ball is under which in this case equals 9.81 
's' is the distance it covers
Thus for maximum height applying the values in the equation we get

Using the same equation we can find the speed of the ball when it reaches 15 meters of height as

the time it takes to reduce the velocity to this value can be found by first equation of kinematics as
