Finding M1 in a Mass Sliding Problem with an Angle and Friction

AI Thread Summary
The discussion focuses on solving a physics problem involving two masses, M1 and M2, connected by a frictionless pulley, with M2 accelerating downwards. The user initially breaks down the forces acting on M1, calculating the normal force and tension but encounters an error in the use of sine and cosine functions. After receiving feedback, they realize they mixed up the sine and cosine components in their calculations. The conversation emphasizes the importance of correctly applying trigonometric functions in physics problems. Ultimately, the user corrects their approach with guidance from others in the thread.
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Homework Statement


M1 and M2 are two masses connected as shown.
https://loncapa2.physics.sc.edu/res/msu/physicslib/msuphysicslib/09_Force_and_Motion/graphics/prob75_fricpullplane.gif
upload_2016-10-6_16-47-34.png

The pulley is light and frictionless. Find the mass M1, given that M2 (3.50 kg) is moving downwards and accelerates downwards at 2.99 m/s2, that θ is 20.0°, and that μk is 0.470.

Homework Equations


F = ma

The Attempt at a Solution


So I have broken down the components of the forces especially for M1 because the Mg force has the components sin and cos. I found the force in the y direction of M1 to be Fn=M1gSin(theta). Then I found the x direction to be T(tension)-u(friction)Fn-M1gCos(theta)=M1a. Which would make T= M1(ugSin(theta) + gCos(theta) +a). And for block 2 I have T = M2(g-a). Then I set the T's equal to each other and solve for M1 but it seems to be wrong.
 
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Ok I think I got it
 

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Are you sure you haven't got ##\cos## and ##\sin## mixed up?
 
PeroK said:
Are you sure you haven't got ##\cos## and ##\sin## mixed up?
I did... Thank you so much!
 
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