When a fan is turned off, its angular speed decreases from 10 rad/s to 6.3 rad/s in 5.0 s. what is the magnitude of the average angular acceleration of the fan

Explanation:

We have final angular speed of the fan

Initial angular velocity of the fan

The angular speed of the is changes from 410 rad/sec to 6.3 rad/sec in 5 sec

So time taken t = 5 sec

From first equation of motion we know that putting the values

negative sign of the acceleration shows that speed of the fan is decreasing in nature which is given in the question  

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

another example of kinetic energy would be,

kinetic energy   >     moving energy

answer   >   letter choice (c),   a hammer falling off a table.

hope that !                                         : )