The tub of a washer goes into its spin cycle, starting from rest and gaining angular speed steadily for 7.00 s, at which time it is turning at 5.00 rev/s. At this point, the person doing the laundry opens the lid, and a safety switch turns off the washer. The tub smoothly slows to rest in 14.0 s. Through how many revolutions does the tub turn while it is in motion?

Respuesta :

Answer:

The no. of revolutions does the tub turn while it is in motion is = 52.51 revolutions

Explanation:

Given data

[tex]\omega_1[/tex] = 0

[tex]\omega_2[/tex] = 5 [tex]\frac{rev}{sec}[/tex]

Time taken = 7 sec

(1). The angular acceleration is given by

[tex]\alpha = \frac{d \omega}{dt}[/tex]

[tex]\alpha = \frac{5}{7}[/tex]

[tex]\alpha = 0.714 \frac{rev}{s^{2} }[/tex]

We know that from the equation of motion

[tex]\omega_2^{2} = \omega_1^{2} + 2 \alpha \theta_1[/tex]

[tex]5^{2} = 0 + 2 (0.714) \theta_1[/tex]

[tex]\theta_1 = 17.5 \ rev[/tex]  -------- (1)

(2). The angular acceleration is given by

[tex]\alpha = \frac{d \omega}{dt}[/tex]

[tex]\alpha = - \frac{5}{14}[/tex]

[tex]\alpha =[/tex] - 0.357 [tex]\frac{rev}{s^{2} }[/tex]

We know that from the equation of motion

[tex]\omega_2^{2} = \omega_1^{2} + 2 \alpha \theta_2[/tex]

[tex]0^{2} = 5^{2} + 2 (-0.357) \theta_2[/tex]

[tex]\theta_2[/tex] = 35.01 rev  -------  (2)

Total no of revolution made by the machine is

[tex]\theta = \theta_1 + \theta_2[/tex]

[tex]\theta =[/tex] 17.5 + 35.01

[tex]\theta =[/tex] 52.51 rev

Therefore the no. of revolutions does the tub turn while it is in motion is = 52.51  rev

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