It will be a straight horizontal line on the graph
In physics, there are empirical values for common important parameters. For example, the speed of sound is equal to 340 meters per second. Unlike the speed of light, the speed of sound is dependent on temperature and pressure. But in standard room conditions, the speed is 340 m/s. Using this value of speed, we can find the depth given the time. You should also note that the distance the echo travels is exactly the same distance that object travelled. Therefore,
Distance = 340 m/s * 6 seconds
Distance = 2,040 meters deep
Describing motion from each frame of reference:
Since observer A is on one of the train's cars, he will find that he is at rest with respect to the train even when it is pulling away because, he is also moving with respect to the train.
Observer B on the stationary platform will observe that the train is pulling away from the station towards the right of the platform. as is described
Observer C will notice that the train is approaching him in the opposite direction at a speed which is the sum of the speeds at which both the train are traveling
If the conductor applies brakes on the train, since the platform is a stationary frame of reference. The motion will be observed as a simple decelerationg. he will observe that the force due to the brakes will cause the velocity of the train with respect to the train to decrease
Universal law of gravitation effects all objects alike . There will be a constant force of gravity acting on the train that will keep the train on its tracks. The tracks in turn exert a reaction force on the train. There will not be any affect on the train's motion as such( assuming that the train is moving along the tracks and gravitational force is exactly perpendicular)
Answer:
Acceleration due to gravity will be 
Explanation:
We have given gauge pressure P = 3.8 atm = 3.8×101325 = 385035 Pa
Depth h = 24.3 m
Density 
We have find the acceleration due to gravity at the surface of planet
We know that pressure is given by

So 

Acceleration due to gravity will be 