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.

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1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.