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A uniform solid cylinder of mass M=1.5kg and radius R=8cm is pivoted horizontally so that it is free to rotate. A mass m=2kg is suspended by the wound string around the cylinder. The system is released from rest. Calculate the acceleration of the mass m. Given the moment of inertia of the solid cylinder, I= 1/2MR^2.

a) 3.5m/s^ 2

b) 2.5m/s^ 2

c) 4.0m/s^ 2

d) 5.0m/s^ 2

1 Answer

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Final answer:

Using Newton's second law and the rotational motion equations, the acceleration of the suspended mass is calculated to be approximately 3.27 m/s^2, which is closest to answer option a) 3.5 m/s^2, although it is not an exact match.

Step-by-step explanation:

To calculate the acceleration of the suspended mass m using the given parameters of the uniform solid cylinder, we apply Newton's second law and the rotational equivalent of Newton's second law (torque = moment of inertia x angular acceleration) simultaneously.

First, the torque caused by the hanging mass m on the cylinder is Tau = m*g*R, where R is the radius of the cylinder, g is acceleration due to gravity, and m is the suspended mass. Using the given moment of inertia I = 1/2 * M * R2 for the cylinder, and knowing that torque is also equal to I*alpha (where alpha is the angular acceleration), we can write:

Tau = I*alpha = (1/2 * M * R2)*alpha

Therefore, m*g*R = (1/2 * M * R2)*alpha

After canceling R and rearranging the formula to solve for alpha, we get:

alpha = (2*m*g) / (M*R)

The linear acceleration a of the hanging mass is related to the angular acceleration alpha by a = alpha*R. Substituting the expression we obtained for alpha gives:

a = (2*m*g*R) / (M*R2) = (2*m*g) / (M*R)

Substituting the given values M = 1.5 kg, R = 0.08 m, m = 2 kg, and g = 9.8 m/s2, we find:

a = (2*2 kg*9.8 m/s2) / (1.5 kg*0.08 m)

a = (39.2 kg*m/s2) / (0.12 kg*m)

a = 326.666... m/s2

Upon calculating, we find that the acceleration 'a' is approximately 3.27 m/s2, which is not precisely any of the options given (a) 3.5 m/s2, (b) 2.5 m/s2, (c) 4.0 m/s2, (d) 5.0 m/s2. The closest answer to the calculated acceleration would be option (a) 3.5 m/s2, but please note that it is not exact.

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