(C) the government agency that regulates these types of chemicals
Atoms, molecules, electrons, photons, protons etc.
Answer:
The first part can be solved via conservation of energy.

For the second part,
the free body diagram of the car should be as follows:
- weight in the downwards direction
- normal force of the track to the car in the downwards direction
The total force should be equal to the centripetal force by Newton's Second Law.

where
because we are looking for the case where the car loses contact.

Now we know the minimum velocity that the car should have. Using the energy conservation found in the first part, we can calculate the minimum height.

Explanation:
The point that might confuse you in this question is the direction of the normal force at the top of the loop.
We usually use the normal force opposite to the weight. However, normal force is the force that the road exerts on us. Imagine that the car goes through the loop very very fast. Its tires will feel a great amount of normal force, if its velocity is quite high. By the same logic, if its velocity is too low, it might not feel a normal force at all, which means losing contact with the track.
Answer:
B. 30 m down
Explanation:
In physics we have two types of quantities:
- Scalar quantity: it is a quantity which only has a magnitude (e.g: mass and time are scalar quantities, since they only have a magnitude)
- Vector quantity: it is a quantity which has both a magnitude and a direction (e.g: velocity is a vector quantity, since it has a magnitude (the speed) and a direction)
In this problem, we have:
A. 100 ounces of water --> scalar (this is a volume, which has only a magnitude)
B. 30 m down --> vector (this is a displacement, which has both a magnitude (30 m) and a direction (down)
C. 88 mi/s --> scalar (this is a speed, which has only a magnitude)
D. 45 gallons in a bucket --> scalar (this is a volume, which has only a magnitude)
So, the correct option is B.