Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheelaccelerates uniformly for 10 s and reaches the operating angular velocity of 38 rad/s. the wheel is run at that angular velocity for 30 s and then power is shut off. the wheelslows down uniformly at 2.1 rad/s2until the wheel stops. in this situation, the angularacceleration of the wheel between t = 0 s and t = 10 s is closest to:

a) 6.1 rad/s2
b) 6.8 rad/s2
c) 3.8 rad/s2
d) 4.6 rad/s2
e) 5.3 rad/s2

Angular acceleration during time period t=0 s to t=10 s is

Explanation:

Since, between the time period from t=0 s to t=10 s the wheel is in uniformly accelerated motion . Therefore angular acceleration is constant at that time period.

Using equation of angular motion.

Here,

putting ,

Hence, this is the required solution.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.