I have a question about rotational kinematics and angularspeed. The question is:

Question

I have a question about rotational kinematics and angularspeed. The question is: Theshaft of a pump starts from rest and has an angular accelerationof 4.70 rad/s2 for12 s.
(a) At the end ofthis interval, what is the shaft's angularspeed?
I understand this part, sinceyou would just multiply 4.70 rad/s2 by 12 s and the answer is56.4.
(b) What is the angle through which the shaft hasturned?
I have tried this part and Ido not understand what to do. I thought you would make adiagram and use sine or cosine to find the answers, but I keepgetting the wrong answer.

I have a question about rotational kinematics and angularspeed. The question is: Theshaft of a pump starts from rest and has an angular accelerationof 4.70 rad/s2 for12 s.
(a) At the end ofthis interval, what is the shaft's angularspeed?
I understand this part, sinceyou would just multiply 4.70 rad/s2 by 12 s and the answer is56.4.
(b) What is the angle through which the shaft hasturned?
I have tried this part and Ido not understand what to do. I thought you would make adiagram and use sine or cosine to find the answers, but I keepgetting the wrong answer.

Explanation / Answer

These are very similar to regular position, velocity,acceleration problems distance = velocity * time final velocity = acceleration * time average velocity = 0.5 * a * t (you're averaging your finalvelocity with 0) therefore distance = 0.5 * acceleration * time * time But here, the angle represents distance, so = 0.5 (4.7 rad/s2) * (12s)2 your s2 's cancel and your left with rad which iswhat you want. plug the numbers into your calculator

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