Answer:
Option A
Explanation:
From the question we are told that:
Mass 
Velocity 
Generally the equation for momentum for Ball A is mathematically given by
Initial Momentum



Final Momentum

Therefore

Generally the equation for momentum for Ball B is mathematically given by
Initial Momentum



Final Momentum

Therefore

Option A
Answer:
The magnitude of the electric flux is 
Explanation:
Given that,
Electric field = 2.35 V/m
Angle = 25.0°
Area 
We need to calculate the flux
Using formula of the magnetic flux


Where,
A = area
E = electric field
Put the value into the formula



Hence, The magnitude of the electric flux is 
Answer:
D
Explanation:
transparent_objects that allows light to pass through and can you see through them
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.
Friction is causing the skateboard to stop rolling.