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A pulley is mounted on a frictionless axis and then the pulley is attached to the higher end of the inclined surface. A massless cord is wrapped around the pulley while its other end is tied to a 1.0 kg object. The pulley has a radius of 20 cm and moment of inertia of 0.4 kg m2 . The angle of the surface is 37° and the coefficient of kinetic friction is 0.2. The object is released from rest. The pulley starts to rotate as the object moves and the cord unwinds. Determine the acceleration of the object and the tension in the cord.​

Sagot :

Newton's second law for translational and rotational motion we can find the answer for the acceleration of the body is 0.04 m / s²

Newton's second law says that the sum of the external forces is equal to the product of the mass and the acceleration of a body.

Reference systems are coordinate systems with respect to which to measure and decompose the vectors, in this case we will use a regency system with the x=axis parallel to the plane and a positive direction in the direction of movement, eg the y-axis is perpendicular to the plane. .

In the Attachment we have a free-body diagram of the systems

y-axis

          N -[tex]W_y[/tex] = 0

          N = [tex]W_y[/tex]

x-axis

         Wₓ -fr - T = m a

The friction force is the macroscopic manifestation of the microscopic interactions between the two surfaces, it is represented by the relationship

          fr = μ N

Let's use trigonometry to break down the weight

          cos 37 = [tex]\frac{W_y}{W}[/tex]

          sin 37 = [tex]\frac{W_x}{W}[/tex]

           [tex]W_y[/tex] = W cos 37

           Wₓ = W sin 37

Let's  substitute

           N = mg cos 37

           mg sin 37 - μ m g cos 37 - T = m a             (1)

We use Newton's second law for rotational motion, in the pulley

            τ = I α

             T R =  I α               (2)

The weight and the normal of the pulley pass through its axis of rotation, so the distance is zero and they do not create torque

Linear and rotational variables

              a = α R

              α = a / R

Let's substitute in equation 2

            T R = I a / R

             T = I / R² a

Let's substitute in equation 1

            mg sin 37 - very m g cos 37 - [tex]\frac{I}{R^2}\ a[/tex] = m a

             a = [tex]\frac{g ( sin 37 - \mu \ cos 37 )}{ 1 + \frac{I}{m R^2} }[/tex]

Let's calculate

             a =   [tex]\frac{ 9.8 ( sin 37 - 0.2 cos 37) }{1 + \frac{0.4}{ 1.0 \ 0.20^2} }[/tex]

             a = [tex]\frac{4.33246}{11}[/tex]

             a = 0.39 m / s²

In conclusion using Newton's second law for translational and rotational motion we can find the answer for the eceleration of the body is

               0.39 m /s²

Learn more about Newton's second law here:

https://brainly.com/question/21054429

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