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A 2.8-kg 13-cm-radius cylinder, initially at rest, is free to rotate about the axis of the cylinder. A rope of negligible mass is wrapped around it and pulled with a force of 20 N.
a) What is the magnitude of the torque exerted by the rope.
b) What is the angular acceleration of the cylinder.
c) What is the angular velocity of the cylinder at t = 1.20 s.

Answer :

Answer:

(a). The magnitude of the torque exerted by the rope is 2.6 N-m

(b). The angular acceleration of the cylinder is 109.8 rad/s².

(c). The angular velocity of the cylinder is 131.76 rad/sec.

Explanation:

Given that,

Mass of cylinder = 2.8 kg

Radius = 13 cm

Force = 20 N

(a). We need to calculate the magnitude of the torque exerted by the rope

Using formula of torque

[tex]\tau=F\times r[/tex]

Put the value into the formula

[tex]\tau=20\times13\times10^{-2}[/tex]

[tex]\tau=2.6\ N-m[/tex]

The magnitude of the torque exerted by the rope is 2.6 N-m

(b). We need to calculate the angular acceleration of the cylinder

Using formula of acceleration

[tex]\alpha=\dfrac{\tau}{I}[/tex]

[tex]\alpha=\dfrac{2\tau}{mr^2}[/tex]

[tex]\alpha=\dfrac{2\times2.6}{2.8\times(13\times10^{-2})^2}[/tex]

[tex]\alpha=109.8\ rad/s^2[/tex]

The angular acceleration of the cylinder is 109.8 rad/s².

(c). We need to calculate the angular velocity of the cylinder

Using equation of motion

[tex]\omega=\omega_{0}+\alpha t[/tex]

Put the value into the formula

[tex]\omega=109.8\times1.20[/tex]

[tex]\omega=131.76\ rad/sec[/tex]

The angular velocity of the cylinder is 131.76 rad/sec.

Hence, (a). The magnitude of the torque exerted by the rope is 2.6 N-m

(b). The angular acceleration of the cylinder is 109.8 rad/s².

(c). The angular velocity of the cylinder is 131.76 rad/sec.

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