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 7.00 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 12.0 s. through how many revolutions does the tub turn while it is in motion?
rev

67 revolutions

Explanation:

t = Time taken

= Final angular velocity

= Initial angular velocity

= Angular acceleration

= Number of rotation

Equation of rotational motion

Number of revolutions in the 7 seconds is 24.5

Number of revolutions in the 12 seconds is 42.02

Total total number of revolutions in the 20 second interval is 24.5+42.02 = 66.52 = 67 revolutions

low freq = 100 mhz

low wavelength =101.7m

length = 3x10^8/freq

answer; i believe that the correct answer is (d) a very small amount of mass