Answer:
a) 
b) 
Explanation:
Given the information from the exercise we can calculate the work done by the elevator using the following formula:

a) Considering you and your belongings as a system we know that the elevator is applying a Normal reaction force of:

Since the force applied and the displacement is in the same direction, the work done by the elevator is positive

b) The reaction force applied by the elevator is the same as the weight of the person

Since the force applied and the displacement is in opposite direction, the work done by the elevator is negative

Answer: D. the wave has traveled 97.2 cm in 1 second.
Explanation:
Got it right on edge, hope this helps :)
The contact force is indeed caused by "Contact".
Air resistance is basically a type of friction, which is apparently present providing two object contact.
The rest selections are all interaction force, which is not necessarily caused by contact.
Answer:
Inertia is an object's tendency to keep moving in a straight line unless acted on by an outside force. Centripetal force causes an object to constantly change direction, so the combination of centripetal force and inertia causes an object to move in a circle. Hope it helps and your cute by the way
Explanation: