Law Of Universal Gravition (am I Right?)

In summary, we are asked to estimate the surface gravity of a certain neutron star that has five times the mass of our sun, packed into a sphere with a radius of 10km. Using the formula g = Gm/r^2, we can calculate the surface gravity to be approximately 6.64m/s. To calculate the acceleration of gravity 250km above the Earth's surface, we can use the inverse square law and the mass and radius of the Earth. The g on the surface would be inversely proportional to the square of the radius and proportional to the mass of the Earth times the gravitational constant. The value of g at this distance can be calculated accordingly.
  • #1
heelp
23
0
A certain neutron star has five times the mass of our sun packed into a sphere about 10km in radius. estimate the surface gravity on this monster.

= (5)(1.99 *10^30 =m
10km =r
g = G mass of earth/r^2 = 6.67* 10^ -11 9.95* 10^30/10^2 = 6.64m/s
Is that the right answer?



Calculate the acceleration of gravity 250km above the Earth's surface in terms of g

ar = v^2/r I'm really stuck I would I go about solving this problem? your help will be appreciated.
 
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  • #2
Calculate the acceleration of gravity 250km above the Earth's surface in terms of g

The acceleration of gravity is dependent upon the mass of the Earth and the distance (d) that an object is from the center of the earth. Think a little about the inverse square law.
 
  • #3
A certain neutron star has five times the mass of our sun packed into a sphere about 10km in radius. estimate the surface gravity on this monster.

The value of g on any other planet can be calculated from the mass of the planet and the radius of the planet. The g on the surface would be inversely proportional to the square of the radius and proportional to the Mass of the planet times the gravitational constant.

g = G mass of earth/r^2 = 6.67* 10^ -11 9.95* 10^30/10^2 = 6.64m/s
There was no need to use the mass of the earth. The question is asking you for the g of a star that's 5X the mass of our sun. The equation that you are using is right. You just inserted the wrong values.
 
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  • #4
I should enter the mass off the star? it wan't given
 
  • #5
heelp said:
I should enter the mass off the star? it wan't given
Of course it was. The question says "A certain neutron star has five times the mass of our sun". The mass is indirectly stated. Just loook up the mass of the sun then times it by 5 that's all. Common you can do it :wink:
 
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1. What is the Law of Universal Gravitation?

The Law of Universal Gravitation, also known as Newton's Law of Gravitation, is a physical law that describes the gravitational attraction between two objects with mass. It states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

2. Who discovered the Law of Universal Gravitation?

The Law of Universal Gravitation was first published by Sir Isaac Newton in 1687. It was one of his most famous contributions to physics and is still widely used in modern physics and engineering.

3. How does the Law of Universal Gravitation affect the motion of planets?

The Law of Universal Gravitation is responsible for the elliptical orbits of planets around the sun. The gravitational force between the sun and each planet keeps them in their respective orbits, while the planets' own inertia keeps them moving in a straight line. This balance of forces results in the curved trajectories we observe.

4. Does the Law of Universal Gravitation apply to all objects?

Yes, the Law of Universal Gravitation applies to all objects with mass. This means that not only planets, but also stars, moons, and even everyday objects on Earth, are subject to the force of gravity.

5. How is the Law of Universal Gravitation related to the concept of weight?

The Law of Universal Gravitation is directly related to the concept of weight. Weight is the force of gravity acting on an object, and according to the Law of Universal Gravitation, this force is directly proportional to the mass of the object. This is why objects with greater mass have a greater weight than objects with smaller mass.

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