Velocity as a Vector Quantity
Because the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity.
Solution :
Acceleration due to gravity of the earth, g 

Acceleration due to gravity at 1000 km depths is :




= 8.23 m/s
Acceleration due to gravity at 2000 km depths is :




= 6.73 m/s
Acceleration due to gravity at 3000 km depths is :



= 5.18 m/s
Acceleration due to gravity at 4000 km depths is :




= 3.64 m/s
Answer:
C. 
Explanation:
The acceleration of an object can be found using the equation:

where
v is the final velocity
u is the initial velocity
t is the time it takes for the velocity to change from u to v
In this problem:
u = 30 m/s is the initial velocity of Angelica
v = 84 m/s is the final velocity
t is the time
Substituting into the equation, we find the acceleration:

Answer:
The floor of the ocean is 6120 m deep.
Explanation:
In order to find the depth of the ocean we need to use the speed of the ultrasonic sound 1530 m/s and the time it takes for the echo to comeback. Since the wave is transmitted by the vessel goes to the bottom of the ocean and comeback, it travels the distance between the vessel and the floor two times, so we can divide the time by two. We then have:
D = V*t/2 = 1530*8/2 = 1530*4 = 6120 m