Answer:
The velocity of the freight car decreases.
Explanation:
This question is answered by the conservation of momentum principle.
When the freight car is moving at a certain speed, it has a constant momentum.
We will call this M1.
The equation for M1 will be:
M1 = Mass * Speed
Now when the coal is dumped into the freight car, the Mass increases.
Since conservation of momentum states that the momentum will remain the same. We have:
M1 = (Mass of freight + Mass of coal) * Speed
Since M1 is constant, if the mass increases, the speed had to decrease to keep the equation true.
To solve this problem we will apply the concepts related to the Doppler Effect, defined as the change in apparent frequency of a wave produced by the relative movement of the source with respect to its observer. Mathematically it can be written as
Here,
= Frequency of the source
= Speed of the sound
= Speed of source
Now the velocity we have that
Then replacing our values,
Therefore the frequency of the observer is 1047.86Hz
Options
a. The worker carried the lunch up to the 53rd floor in the elevator.
b. The worker got a ride in a helicopter to the top of the 68-floor building and then carried the lunch down in the elevator to the 53rd floor?
c. The Worker carried it up the stairs to the 53rd floor.
d. Gravitational potential energy does not depend on the path taken.
Answer:
The gravitational Energy would remain the same in all cases.
Explanation:
Gravitational Energy is a conservative energy and its potential energy comes from gravitational actions.
An instance is when someone lifts a weight from the floor to a certain height and then dropped the weight back to the floor; the work done by the field will not be altered at all; it'll be the same throughout.
If otherwise, it'll be against thermodynamics 2nd law of physics because the object would have remaining energy after returning to the starting point,
For this reason, the gravitational potential energy only depends from the height, and is independent from the path taken to reach there.
