Force of gravity of chain links problem

AI Thread Summary
The problem involves two chain links, with the top link weighing 8kg and the bottom link's mass unknown. An upward force of 216N is applied to the top link, causing an acceleration of 2m/s². To find the mass of the bottom link and the force it exerts on the top link, a system of equations using F = ma for each link is recommended. The total force acting on the system must account for both the applied force and the gravitational force, which should be calculated using the correct value of g, approximately 9.81 m/s². The discussion emphasizes the importance of isolating variables and using symbols until the equations are solved.
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Homework Statement


Two chain links are connected together and are suspended by a string. The mass of the top link, link#1 is 8kg, while the mass of the second/bottom link #2 is unknown. If an applied force on the string attached to link #1 of 216N[up], and the links experience an acceleration of 2m/s^2 [up] find the mass of link #2 and the force that link#2 exerts on link1
The only given variables we have are
a= 2 m/s^2
Fa= 216N
g=10N

I'm guessing I have to isolate variables, but I am not sure what equations to use.
 
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Use F = ma where F is the total of the forces on the object.
You must be very clear in your mind what "the object" is. The conventional approach is to do an F = ma for each object and the force of one link on the other then will appear in both equations - you get a system of two equations to solve. Sometimes you can reduce the work by cleverly thinking of the two objects combined as one object and use just one F = ma.
 


Would the total of the forces on the object just be the applied force which is 216?
 


How about gravity?
 


oh right, so then F, being the total of all the forces would be...
216N + 10N
so F=226N
 


No, that 10 N is incorrect. In your first post,
g=10N
should read g = 9.81 m/s².
The force of gravity is mg, which you can't immediately find because you don't know m. Anyway, it is better to stick with symbols like m until you have solved the equation for the quantity you want to find.
 
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