Applications of Newtons Law Question 1

[noasherelol]

Homework Statement

A hockey puck of mass m is attached to a string that passes through a hole in the center of a table. The Hockey Puck moves in a circle or radius r. Tied to the other end of the string, and hanging vertically beneath the table is Mass M.. Assuming the table top is perfectly smooth, what speed must the hockey puck have if the mass M is to remain at rest?

Homework Equations

F=mv^2/r

The Attempt at a Solution

The Sum of all forces on the axis = mv^2/r
r-vsin(theta)=mv^2/r

Im think I am wrong with this


*I might have other questions to ask later, I am really stuck on Newtons laws in physics

 

[Epsillon]

Alright so Fg = Fc

Mg= mv^2/r



You do not have any numbers for this??

 

[noasherelol]

nope it never gave numbers, i think this is why I am so confused with it

 

[heth]

nope it never gave numbers, i think this is why I am so confused with it

Look at it as an algebra question once you've set up the equations. Rearrange it so that the thing they're asking you for is on its own on the left hand side of the equation.

(You should be doing this anyway even if you have numbers to plug in. So this is like a question where you have numbers - but without putting the numbers in at the end.)