Assessment
Identify the Variables!
In rotational kinematics  the variables are:
For each problem, you need to find each numbers and assign it to one of these five variables. Here's an example problem:
"a motor is initially at rest and it picks up speed at 1.2 rad/s^{2} for 12 s until it reaches an angular velocity of 14 rad/s, in which time it turns thru 173 revolutions"
then you need to identify the following variables:
You have two things that help you nail down which number goes with what variable:
Solve the Formula and the Problem!
A typical problem might read "a wheel is turning at 6 rad/s when it speeds up at 2 rad/s^{2} for 3 s. Find the angle it turns thru"
First: find out what we already know
Second: figure out what we want to find out
Third: find a formula that has those four variables  ω_{O} , α, t and θ
Fourth: if the problem needs to be algebraically solved for the
missing variable, do it. Then plug in the numbers and solve. In
this problem we don't need to rearrange the formula as θ is already
by itself.θ =(6 rad/s) (3 s) + 1/2 (2 rad/s^{2} )(3
s)^{2}
= 18 rad + 9 rad
= 27 rad
Question 1 (1 point)
Match the following numbers with the right variable name  remember, the units are your best friend!
A gear moving at 2 rad/s accelerates at 1.4 rad/s^{2} to a speed of 12 rad/s. Find the angle the gear moves through.
Question 1 options:


Question 2 (1 point)
Same problem: A gear moving at 2 rad/s accelerates at 1.4 rad/s^{2} to a speed of 12 rad/s. Find the angle it moves thru.
Looking at the variables named in the last problem, which formula would be the best to use?
Question 2 options:







Question 3 (1 point)
Same problem: A gear moving at 2 rad/s accelerates at 1.4 rad/s^{2} to a speed of 12 rad/s. Find the angle the gear moves through.
Question 3 options:







Question 4 (1 point)
A wheel spins at 15 rad/s. How long does it take to turn thru 500 rad?
Question 4 options:







Question 5 (1 point)
A drill is moving at 6 rad/s when it speeds up at 2 rad/s^{2} for 3 s. Find the angular velocity at the end of the problem
Question 5 options:







Question 6 (1 point)
A motor is accelerating at 0.6 rad/s^{2} while it covers 20 rad. If it reaches a final angular velocity of 8 rad/s, find the initial angular velocity.
Question 6 options:







Question 7 (1 point)
An rotating disk starts from rest and accelerates at 1 rad/s^{2} for 17 s until it takes off. Determine the angle.
Your Answer:Question 7 options:
Answer 
Question 8 (1 point)
An merrygoround starts from rest and has an angular acceleration of 2 rad/s^{2} and covers 390 rad. Determine the time it takes.
Your Answer:Question 8 options:
Answer 
Question 9 (1 point)
An saw blade starts from 4 rad/s and accelerates at 3 rad/s^{2} and covers 354 rad. Determine the time it takes.
Note, the formula will still have t and t^{2} so it's a quadratic equation, and we can use the quadratic formula:
Steps:
Your Answer:Question 9 options:
Answer 
Question 10 (1 point)
Sometimes you have to do the problem in two steps:
A car moving at 22 rad/s comes to a stop in 12 s. Find the angle it moves thru.
Your Answer:Question 10 options:
Answer 
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