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sodium40mg
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Homework Statement
Three blocks are connected by two different strings over two pulleys. Assume no friction between the pulleys and the rope segments.
- Green mass = 13 kg
- Red mass = 18 kg
- Blue mass = 23 kg
The coefficient of friction between the masses and the surface is 0.20.
Find the tensions between the masses.
Homework Equations
- fg = mg
- fnet = ma
- fnet = total forces
The Attempt at a Solution
So what I'm thinking of doing is like sectioning each mass.
Green mass
m = 13 kg
Fnet = T1 - Fg1 - Ff
(13)(a) = (13)(9.8)(sinθ1) - (0.20)(13)(9.8)(cosθ1) - T1
So T1 and a is unknown for the Green mass
Red mass
m = 18 kg
Fnet = T2 - T1
(18)(a) = T2 - T1
Three unknowns here.
Blue mass
m = 23 kg
Fnet = T2 - Fg3 - Ff
(23)(a) = T2 - (23)(9.8)(sinθ2) - (0.20)(23)(9.8)(cosθ2)
Two unknowns here.The easiest thing to do now would be to rearrange so that each equals a tension and then substitute that into the other equation to find acceleration. Once I got acceleration, I would just be able to substitute and find the tensions.
But what I'm unsure about is whether the equations are right. Are the signs right? Did I subtract something I should've added or vice versa? Any help would be appreciated.