Gravitational Near Earth Surface.

AI Thread Summary
The discussion centers on calculating the minimum mass of a neutron star with a radius of 7 km that rotates at 1000 revolutions per second, ensuring surface material remains in place. The user attempts to solve the problem using the formula but receives feedback indicating a mistake in not cubing the radius value. The correct approach involves applying gravitational equations while considering the effects of rapid rotation. The conversation highlights the importance of careful mathematical application in physics problems. Properly cubing the radius is crucial for accurate results in this context.
asdf122345
Messages
2
Reaction score
0

Homework Statement



Certain neutron stars (extremely dense stars) are believed to be rotating at about 1000 rev/s. If such a star has a radius of 7 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation?

Homework Equations



cramster-equation-201031601226340429448270400007570.gif




The Attempt at a Solution



(7x10^3)(1000*2pi)/6.67*10^-11= 2.0301495

I'm getting it wrong. Any hints why?
 
Physics news on Phys.org
You forgot to cube the value of R.

ehild
 
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

Gravitational Potential Energy Project Thor
Replies
8
Views
2K
Find the attractive force of gravity between two objects
Replies
8
Views
2K
Need help with gravitation problem
Replies
1
Views
2K
Weight of person on Earth, and on a different planet's surface?
Replies
11
Views
2K
Gravitational potential energy traveling from earth to mars
Replies
7
Views
3K
Change in gravitational potential below the surface of the Earth
Replies
4
Views
3K
Calculating Magnetic Flux Density for an Electron Orbiting Near Earth's Surface
Replies
3
Views
2K
Why does the gravitational force decrease below the Earth's surface?
Replies
10
Views
3K
Newton's law of universal gravitation
Replies
2
Views
1K
Gravitational Potential Energy questions near the surface of a planet
Replies
8
Views
2K

Hot Threads

Recent Insights

Back
Top