Question

Wonder Woman and Superman fly to an altitude of 1510 km, carrying between them a chest full of jewels that they intend to put into orbit around Earth. They want to make this tempting treasure inaccessible to their evil enemies who are trying to gain possession of it, yet keep it available for themselves for future use when they retire and settle down. But perhaps the time to retire is now! They accidentally drop the chest, which leaves their weary hands at rest, and discover that they are no longer capable of catching it as it falls into the Pacific Ocean.
At what speed does the chest impact the surface of the water? Ignore air resistance, although in the real world it would make a world of difference. The radius and mass of Earth are 6370 km and 5.98 × 1024 kg, respectively.

Answer 1

Answer:

10061.56 m/s

Explanation:

Gravitation potential of a body in orbit from the center of the earth is given as

Pg = -GM/R

Where G is the gravitational constant 6.67x10^-11 N-m^2kg^-2

M is the mass of the earth = 5.98x10^24 kg

R is the distance from that point to the center of the earth = r + Re

Where r is the distance above earth surface, Re is the earth's radius.

R = 1510 km + 6370 km = 7880 km

Pg = -(6.67x10^-11 x 5.98x10^24)/7880x10^3

Pg = -50617512.69 J/kg

The negative sign means that the gravitational potential is higher away from earth than it is at the earth's surface (it shows convention).

This indicates the kinetic energy per kilogram that the chest of jewel will fall with to earth.

For the jewel chest, the velocity V will be

0.5v^2 = 50617512.69

V^2 = 101235025.4

V = 10061.56 m/s