Ratio of two masses connected by pulley

AI Thread Summary
The discussion focuses on finding the ratio of two masses, m1 and m2, connected by a pulley, considering the effects of friction and acceleration. The initial attempt to derive the ratio resulted in an incorrect equation that included trigonometric functions, which was pointed out as a mistake. The correct formula should not depend on Cosθ or Sinθ, leading to the realization that the expression should be m1/m2=(g(Cosθ - μSinθ))/(g-a). Participants also discussed verifying the correctness of the equations by testing extreme cases, such as θ=π/2, to ensure the components were accurately represented. Overall, the conversation emphasizes the importance of correctly applying physics principles to solve the problem.
Tasha9000
Messages
8
Reaction score
0

Homework Statement

[/B]
Figure 1) Block 1, of mass m1, is connected over an ideal (massless and frictionless) pulley to block 2, of mass m2, as shown. Assume that the blocks accelerate as shown with an acceleration of magnitude a and that the coefficient of kinetic friction between block 2 and the plane is μ.

Find the ratio of the masses m1/m2.
Express your answer in terms of some or all of the variables a, μ, and θ, as well as the magnitude of the acceleration due to gravity g.
MLD_2l_2_v2_2_a.jpg

Homework Equations


Fnet=ma
Ff=muN
W=mg

The Attempt at a Solution



+ /x is direction of acceleration

Forces on m2

y-axis
N - mgy=0

x-axis
T - m2gx-Ff=m2a

T - m2g Cosθ - μm2Sinθ=m2a

Forces on m1

m1g - T = m1a

Attempt

I just put all the equations into one and got:

m1/m2=(g(Cosθ - μSinθ))/(g/a)

but it still says it's wrong. It says the final answer doesn't depend on Cosθ or Sinθ
 
Physics news on Phys.org
Tasha9000 said:

Homework Statement

[/B]
Figure 1) Block 1, of mass m1, is connected over an ideal (massless and frictionless) pulley to block 2, of mass m2, as shown. Assume that the blocks accelerate as shown with an acceleration of magnitude a and that the coefficient of kinetic friction between block 2 and the plane is μ.

Find the ratio of the masses m1/m2.
Express your answer in terms of some or all of the variables a, μ, and θ, as well as the magnitude of the acceleration due to gravity g.
MLD_2l_2_v2_2_a.jpg

Homework Equations


Fnet=ma
Ff=muN
W=mg

The Attempt at a Solution



+ /x is direction of acceleration

Forces on m2

y-axis
N - mgy=0

x-axis
T - m2gx-Ff=m2a

T - m2g Cosθ - μm2Sinθ=m2a

Forces on m1

m1g - T = m1a

Attempt

I just put all the equations into one and got:

m1/m2=(g(Cosθ - μSinθ))/(g/a)

but it still says it's wrong. It says the final answer doesn't depend on Cosθ or Sinθ

it should be m1/m2=(g(Cosθ - μSinθ))/(g-a)

I also probably messed up the components but I tried both ways
 
To check whether I have sin and cos the right way round, I consider an extreme case, like ##\theta=\pi/2##. Do your equations look right for that case?
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'
Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is(Figure 2): F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...

Similar threads

Back
Top