Extremely frustrated - inclined plane problem w/ friction

In summary: The conversation discusses two scenarios - when M1 is initially moving up the incline and when it is initially moving down. In both cases, the net force on M1 is calculated using the equation (Ʃm)*a = (M2*g) - [(μ*N) + (mg*sin(59))]. The direction of acceleration is chosen to be positive in the direction of motion of the masses.
  • #1
iJamJL
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Homework Statement


Mass M1 (6.58 kg) is on a rough inclined plane that makes an angle θ = 59o with the horizontal. The coefficient of kinetic friction between M1 and the incline is μk = 0.18. A rope is attached to M1, passes over a frictionless pulley, and is attached to mass M2 = 7.30 kg which hangs freely.
(a) If M1 is initially moving up the incline: find the magnitude of the acceleration of the masses.
(b) If M1 is initially moving down the incline: find the magnitude of the acceleration of the masses.


Homework Equations


Frictional force = μk * N
F=mg
Components


The Attempt at a Solution


I drew the inclined plane and labeled all of the forces. To solve part (a), M1 is moving up the incline, making the frictional force in the direction of the bottom of the plane, parallel to the plane. The total frictional force should be (μ*N) + (mg*sin(59)), if I am correct. The net force on M1 would be (M2*g) - [(μ*N) + (mg*sin(59))] = (Ʃm)*a

We then divide by Ʃm to get the acceleration.

For part (b), it's the same idea. I would solve it like this:

(mg*sin(59)) - [(M2*g) + (μ*N)] = (Ʃm)*a

We divide by Ʃm again to find the acceleration.

Am I taking the wrong approach? Also, if I'm not being clear on any part, let me know.
 
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  • #2
If you mean M1 on m your equations are correct. Explain the chosen direction of acceleration in both cases, what direction you take positive.

ehild
 

Related to Extremely frustrated - inclined plane problem w/ friction

1. What is an inclined plane?

An inclined plane is a simple machine that consists of a flat surface that is at an angle to the ground. It is commonly used to make it easier to move objects from a lower elevation to a higher elevation by reducing the amount of force needed to lift the object.

2. How does friction affect an inclined plane problem?

Friction is a force that opposes motion between two surfaces in contact. In the case of an inclined plane, friction acts in the opposite direction of the object's motion, making it more difficult to move the object up the incline. This means that more force is needed to overcome the friction and move the object up the incline.

3. What is the formula for calculating the force required to move an object up an inclined plane?

The formula for calculating the force required to move an object up an inclined plane is F = mg(sinθ + μcosθ), where F is the force needed, m is the mass of the object, g is the acceleration due to gravity, θ is the angle of the incline, and μ is the coefficient of friction.

4. How does the angle of the incline affect the force needed to move an object?

The steeper the angle of the incline, the greater the force needed to move an object up the incline. This is because the steeper the incline, the more the weight of the object is acting against the motion, making it more difficult to overcome with the applied force.

5. What factors can affect the coefficient of friction in an inclined plane problem?

The coefficient of friction can be affected by the type of material the object is moving on, the smoothness of the surfaces in contact, and the force pressing the surfaces together. Additionally, the coefficient of friction can vary depending on whether the object is in motion or at rest.

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