Aceiling fan is turned on and reaches an angular speed of 120 rev/min in 20 s. it is then turned off and coasts to a stop in an additional 40 s. the ratio of the average angular acceleration for the first 20 s to that for the last 40 s is which of the following?

a.2
b.-0.5
c.0.5
d.-2

option D

Explanation:

given,

angular speed of the fan = 120 rev/min

time = 20 sec

After 40 s fan comes to rest

ration angular acceleration of the first 20 s to last 40 s.

angular acceleration for first 20 s

for last 40 s

now, ratio

hence, the correct answer is option D

the higher the current the higher the mag field around it the higher the influence on the compass

  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is