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.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.