Gravitational and circular motion

[physicsgirl12]

The Problem Statement
1) The gravitational force of attraction between Earth and sun is 3.52X10^22 Newtons. Calculate the mass of the sun. (Include equation and how you solved it)

2) The centers of two 15 kg spheres separated by 3 meters. The magnitude of the gravitational force between the two surfaces is approximately
A. 1.11x10^-10 N B. 1.67x10^-9 N C. 3.34x10^-10 N D. 5.00x10^-9 N


1) Equation F= G( Mm/r^2)?
Attempt at solving:
3.52x10^22= 6.67x10^-11(Mm/6.37x10^6 squared)?
(3.52x10^22/6.67x10^-11)/6.37x10^6 squared)
I solved it but i got a weird number
-6.55x10^-22
I know its wrong


2) Equation:Fc= mv^2/r
Attempt at solving:
(6.67x10^-11)(15)(15)/ 1.5)?
1.001x10^-11?
its wrong

 

[PhanthomJay]

Hi, physicsgirl12! Forum rules require that you list relevant equations and show an attempt at a solution. Follow the template, edit your post, and resubmit; someone will then gladly assist.

 

[gneill]

The Problem Statement
1) The gravitational force of attraction between Earth and sun is 3.52X10^22 Newtons. Calculate the mass of the sun. (Include equation and how you solved it)

2) The centers of two 15 kg spheres separated by 3 meters. The magnitude of the gravitational force between the two surfaces is approximately
A. 1.11x10^-10 N B. 1.67x10^-9 N C. 3.34x10^-10 N D. 5.00x10^-9 N


1) Equation F= G( Mm/r^2)?
Attempt at solving:
3.52x10^22= 6.67x10^-11(Mm/6.37x10^6 squared)?
(3.52x10^22/6.67x10^-11)/6.37x10^6 squared)
I solved it but i got a weird number
-6.55x10^-22
I know its wrong

Can you explain what the 6.37 x 10^6 number represents? Why don't you show your equation for the mass of the sun symbolically first, before plugging in the numbers.

2) Equation:Fc= mv^2/r
Attempt at solving:
(6.67x10^-11)(15)(15)/ 1.5)?
1.001x10^-11?
its wrong

Your numerical equation doesn't match the equation you started with. Perhaps you meant to write Newton's law of gravitation? Anyways, can you explain your reason for your choice of value for r?