A uniform disk of radius 0.2 m and mass m = 16 kg is mounted on a nearly frictionless axle. A string is wrapped tightly around the disk and pulled with a constant force of F = 1 N. After a while the disk has reached an angular speed of !0 = 1.2 rad/s. What is its angular speed 1.5 s later?

Respuesta :

Answer:

ω = 2.13rad/s

Explanation:

Given

F = 1N = force applied, m = 16kg, R = 0.2m

ωo = 1.2rad/s

t = 1.5s

ω = ?

Where

α = angular acceleration

ωo = initial angular speed

And ω = angular speed at a later time t

For a rigid body rotating about an axis

τ = FR= I×α

I = 1/2×MR² for a uniform disk

FR = (1/2×mR²)×α

= 1/2×mR²×(ω – ωo)/t

Therefore

FR= 1/2×mR²×(ω – ωo)/t

2Ft/mR = ω – ωo

ω = 2Ft/mR + ωo

ω = 2×1×1.5/(16×0.2) + 1.2 = 2.13 rad/s

Newton's second law and kinematics for rotational motion allows to find the result for the angular velocity of the disk is:

          w = 1.24 rad / s

Given parameters

  • The radius of the disk r = 0.2 m
  • The mass of the disk m = 15 kg
  • The applied force F = 1 N
  • The angular velocity wo = 1.2 rad / s

To find

  • The angular velocity for a time of t = 1.5 s

Newton's second law for rotational motion stable a relationship between torque, moment of inertia, and angular acceleration.

          τ = I α

where I is the moemnt inerti and α is the angular acceleration.

The moment of inertia of a disk is tabulated.

          I = ½ m r²

Torque is the product of the force times the arm or perpendicular distance

         τ = F r

Let's substitute

       F r = (½ m r²) α

       α = [tex]\frac{2 F r}{m}[/tex]  

Let's calculate

      α = [tex]\frac{2 \ 1 \ 0.2 }{16}[/tex]  

      α = 0.025 rad / s²

Rotational kinematics studies the rotational motion of bodies, let's use the relation

          w = w₀ + α t

           

Let's calculate

          w = 1.2 + 0.025 1.5

          w = 1.2375 rad / s

          w = 1.24 rad / s

In conclusion using Newton's second law and kinematics for rotational motion we can find the result for the angular velocity of the disk is:

          w = 1.24 rad / s

Learn more here: brainly.com/question/14524058

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