Law Of Universal Gravition (am I Right?)

  • Thread starter Thread starter heelp
  • Start date Start date
  • Tags Tags
    Law Universal
AI Thread Summary
The discussion centers on estimating the surface gravity of a neutron star with five times the mass of the sun and a radius of about 10 km. The correct formula for calculating gravity involves using the gravitational constant and the mass of the star, which can be derived from the sun's mass. Participants clarify that the mass of the neutron star is indirectly provided in the problem statement and emphasize the importance of correctly applying the formula. Additionally, there is a query about calculating the acceleration of gravity 250 km above Earth's surface, highlighting the dependence on distance and mass. The conversation reinforces the need to accurately interpret given values in gravitational calculations.
heelp
Messages
23
Reaction score
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.
 
Physics news on Phys.org
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.
 
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.
 
Last edited:
I should enter the mass off the star? it wan't given
 
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:
 
Last edited:
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Determine the mass of the planet using Newton’s Law of Universal Gravitation
Replies
2
Views
3K
Law of universal gravitation (am I doing it wrong)
Replies
3
Views
1K
Newton's law of universal gravitation
Replies
2
Views
1K
Calculating mass of a planet (Law of Universal Gravitation)
Replies
2
Views
4K
Gravitational Field Strength at the equator and poles
Replies
23
Views
3K
Some homework questions in astrophysics (Kepler's Laws, Newton's Laws)
Replies
6
Views
1K
Applying Newton's Universal Law of Gravitation
Replies
1
Views
1K
Variation of escape velocity with equal surface gravity
Replies
7
Views
1K
Find the attractive force of gravity between two objects
Replies
8
Views
2K
Inverse square law of gravitation and force between two spheres
Replies
8
Views
2K

Hot Threads

Recent Insights

Back
Top