The International Space Station (ISS) orbits the Earth in a nearly circular orbit that is 345 km above the Earths surface. (a) How many hours does it take for the ISS to make each orbit? (b) Some of the experiments performed by astronauts in the ISS involve the effects of “weightlessness” on objects. What gravitational force does the Earth exert on a 10 kg object in the ISS? Express your answer in newtons and as a fraction of the force that Earth would exert on the object at Earth’s surface. (c) Considering your answer in part 2(b) above, how can an object be considered weightless in the ISS? 3. Two planets, both of mass m, are separated by a distance d. Their relative velocity is negligible, and there is an inertial frame in which both planets are essentially at rest. The gravitational potential u(r) at the position r in the presence of the two planets, located at R1 and R2, is given as u(r) = − Gm R1 −r − Gm R2 −r . This problem takes place far out in space and there are no other massive objects in the vicinity of the two planets. (a) Draw a graph of u as a function of position (r) along the line between the two planets. (b) There are space stations Alpha and Beta located on the line between the planets. Both space stations are at rest with respect to the planets. Alpha is at distance d 4 from planet 1 and Beta is at distance d 3 from planet 2. A projectile of mass m is fired from station Alpha, with its velocity v pointing directly at planet 2. What is the minimum speed v
Gravitational force
In nature, every object is attracted by every other object. This phenomenon is called gravity. The force associated with gravity is called gravitational force. The gravitational force is the weakest force that exists in nature. The gravitational force is always attractive.
Acceleration Due to Gravity
In fundamental physics, gravity or gravitational force is the universal attractive force acting between all the matters that exist or exhibit. It is the weakest known force. Therefore no internal changes in an object occurs due to this force. On the other hand, it has control over the trajectories of bodies in the solar system and in the universe due to its vast scope and universal action. The free fall of objects on Earth and the motions of celestial bodies, according to Newton, are both determined by the same force. It was Newton who put forward that the moon is held by a strong attractive force exerted by the Earth which makes it revolve in a straight line. He was sure that this force is similar to the downward force which Earth exerts on all the objects on it.
The International Space Station (ISS) orbits the Earth in a nearly circular orbit that is 345
km above the Earths surface.
(a) How many hours does it take for the ISS to make each orbit?
(b) Some of the experiments performed by astronauts in the ISS involve the effects of
“weightlessness” on objects. What gravitational force does the Earth exert on a 10 kg
object in the ISS? Express your answer in newtons and as a fraction of the force that
Earth would exert on the object at Earth’s surface.
(c) Considering your answer in part 2(b) above, how can an object be considered weightless
in the ISS?
3. Two planets, both of mass m, are separated by a distance d. Their relative velocity is negligible, and there is an inertial frame in which both planets are essentially at rest. The gravitational potential u(r) at the position r in the presence of the two planets, located at R1 and
R2, is given as
u(r) = −
Gm
R1 −r
−
Gm
R2 −r
.
This problem takes place far out in space and there are no other massive objects in the vicinity
of the two planets.
(a) Draw a graph of u as a function of position (r) along the line between the two planets.
(b) There are space stations Alpha and Beta located on the line between the planets. Both
space stations are at rest with respect to the planets. Alpha is at distance d
4
from planet
1 and Beta is at distance d
3
from planet 2. A projectile of mass m is fired from station
Alpha, with its velocity v pointing directly at planet 2. What is the minimum speed v
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