I believe it is C i am not sure
Answer:
Friction always acts in the direction opposing motion. This means if friction is present, it counteracts and cancels some of the force causing the motion (if the object is being accelerated).
Explanation:
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
Answer:
n=2.053
Explanation:
We will use Snell's Law defined as:
Where n values are indexes of refraction and 
values are the angles in each medium. For vacuum, the index of refraction in n=1. With this we have enough information to state:
Solving for 
yields:
Remember to use degrees for trigonometric functions instead of radians!
Answer:
Explanation:
F = mω²R
F = 15(2π/8.5)²(7.8)
F = 63.93044788...
F = 63.9 N
answer a) is the closest. No idea how they got a value that low unless they used a poor approximation for π.
