I think the correct answer is is D.
Answer:
c. 2.6 h
Explanation:
The longest time spent over dinner is the time that you have available minus the minimum possible time spent in the trip.
The time of the trip is found using:
t = 
Where distance is d and velocity is v. The time will be minimum at maximum velocity. Replacing with the data we have:
Ttrip =
= 8.1818 h
Tdinner = 10.8h - 8.1818 h = 2.6181h
that aproximates 2.6 h.
At the frequency of 5 MHz, the period of the oscillations is 1/5meg. That's a period of 1/5 microsecond.
There are 5 full cycles in one full microsecond, and there are 2.5 full cycles in a 0.5 us pulse.
You'll have to decide for yourself how damped a pulse of 2.5 cycles is, because the parameters of the definition are corrupted in the question.
Answer:
The elastic potential energy of the spring change during this process is 21.6 J.
Explanation:
Given that,
Spring constant of the spring, 
It extends 6 cm away from its equilibrium position.
We need to find the elastic potential energy of the spring change during this process. The elastic potential energy of the spring is given by the formula as follows :

So, the elastic potential energy of the spring change during this process is 21.6 J.