Answer:
B.
Explanation: Mechanical waves need a medium to travel.
You could attach both springs to the ceiling and hang the same mass from both. The one that stretches less has the larger spring constant value.
Answer:
Net work done, 
Explanation:
It is given that,
Mass of the plane, 
Acceleration of the plane, 
(upwards)
Distance covered, d = 34.3 m
We need to find the net work done on the plane as it accelerates upward. The product of force and the distance covered is equal to work done. It is given by :
W = 308700 J
or
So, the net work done on the plane is 
. Hence, this is the required solution.
Since the train is moving at constant speed and direction, the velocity of the train is constant. According to Newton's First Law of Motion, when an object is moving at constant speed in a straight line(aka constant velocity), the resultant force experienced by the train is 0N. Since you're on the train, the resultant force experienced by you is 0N, thus, you do not have to exert a force to remain balanced.
