Answer:
The objects must be different temperatures.
Explanation:
For heat to flow between two objects, heat must be flowing between them. The thermal gradient allows for the flow of heat. Heat is a form of energy that is dissipated from one place to another based on temperature difference.
Temperature is the degree of hotness or coldness of body. It is power by heat energy between two bodies.
Heat generally flows from a body at high temperature to one at low temperature. When thermal equilibrium is established and both bodies have the same temperature, heat will stop to flow.
Answer:
Part a)

Part B)

Part C)

Explanation:
Part A)
As we know that ball is hanging from the top and its angle with the vertical is 20 degree
so we will have






Part B)
Here we can use energy theorem to find the distance that it will move




Part C)
At terminal speed condition we know that




The conversion from gallons to liters is 1 = 3.785.
Keeping this in mind...
42 x 3.785 = 158.97 liters.
If rounding, there are about 159 liters of oil in a barrel.
Answer : C. Pascal's principle.
Explaination : Pascal's principle (well-known as Pascal's law) states that if a closed container contains a fluid at rest, then a small change in pressure at one side of the fluid is transmitted to each and every part of the fluid and also to the walls of the container without any loss. In a hydraulic lift, we need the same mechanism to work and so we take the help of Pascal's principle.
Hence, the correct option is C. Pascal's principle.