AP Physics Multiple Choice Question

In summary: Just remember to include the units in your answer. Great job! :) In summary, a force of 12 N applied tangentially to a wheel with a radius of 0.70 m and rotational inertia of 3.0 kg-m2 will result in an angular acceleration of 2.8 rad/s2. If the force acts for 20 seconds, the kinetic energy of the spinning wheel will be 4.4 x 102 joules.
  • #1
girlphysics
43
0
5. A force of 12 N is applied tangentially to the rim of a wheel with radius 0.70 m and rotational inertia 3.0 kg-m2. What angular acceleration results?
a) 2.6 rad/s2 b) 2.8 rad/s2 c) 3.2 rad/s2 d) 3.4 rad/s2 e) none of these
____6. If the force in question #5 acts for 20 s, what will be the kinetic energy of the spinning wheel?
a) 4.7 x 103 j b) 4.4 x 102 j c) 4. 7 x 10 j d) 84 j e) none of the above answers is within 10 % of the correct value

I figured out number 5 to be B.) 2.8 rad/s by rF/I from Torque=Ia
For 6, when I solve using K=1/2Iw^2, and using 2.8 rad/s^2 divided by 20 seconds to get the angular velocity of .14 rad/s, I get a really small number, like .03. What am I doing wrong?
 
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  • #2
girlphysics said:
5. A force of 12 N is applied tangentially to the rim of a wheel with radius 0.70 m and rotational inertia 3.0 kg-m2. What angular acceleration results?
a) 2.6 rad/s2 b) 2.8 rad/s2 c) 3.2 rad/s2 d) 3.4 rad/s2 e) none of these
____6. If the force in question #5 acts for 20 s, what will be the kinetic energy of the spinning wheel?
a) 4.7 x 103 j b) 4.4 x 102 j c) 4. 7 x 10 j d) 84 j e) none of the above answers is within 10 % of the correct value

I figured out number 5 to be B.) 2.8 rad/s by rF/I from Torque=Ia
For 6, when I solve using K=1/2Iw^2, and using 2.8 rad/s^2 divided by 20 seconds to get the angular velocity of .14 rad/s, I get a really small number, like .03. What am I doing wrong?

Suppose this was a regular linear kinematics problem where you have an acceleration a and you want to find the velocity v after some time t, what's the formula?
 
  • #3
gneill said:
Suppose this was a regular linear kinematics problem where you have an acceleration a and you want to find the velocity v after some time t, what's the formula?

you can't divide acceleration/time to get velocity?
 
  • #4
girlphysics said:
you can't divide acceleration/time to get velocity?

Nope. What would the resulting units be?
 
  • #5
(rad/s^2 )/ s
so rad/s which is velocity?
I don't know something in my brain isn't connecting
 
  • #6
gneill said:
Nope. What would the resulting units be?

No it would be rad/s^3. duh omg
 
  • #7
girlphysics said:
No it would be rad/s^3. duh omg

:smile:

So, better to multiply acceleration by time then... :wink:
 
  • #8
thank you! I got A I hope its right!
 
  • #9
girlphysics said:
thank you! I got A I hope its right!

Looks good.
 

Related to AP Physics Multiple Choice Question

What is AP Physics Multiple Choice Question?

AP Physics Multiple Choice Question is an assessment tool used to test students' understanding of concepts and principles in AP Physics. It consists of a set of multiple choice questions that cover various topics in physics, such as mechanics, electricity and magnetism, and thermodynamics.

How many questions are typically included in an AP Physics Multiple Choice Question test?

An AP Physics Multiple Choice Question test usually consists of 35 questions, with 25% of the questions covering mechanics, 30% covering electricity and magnetism, and 25% covering thermodynamics. The remaining 20% of questions cover miscellaneous topics such as waves and optics.

Are calculators allowed during an AP Physics Multiple Choice Question test?

Yes, calculators are allowed during an AP Physics Multiple Choice Question test. However, they must be approved by the College Board and meet certain requirements, such as not having the ability to store text, formulas, or equations.

How is an AP Physics Multiple Choice Question test scored?

Each question on an AP Physics Multiple Choice Question test is worth one point. The total score is calculated by adding up the number of correct answers. There is no penalty for incorrect or unanswered questions. The maximum score is 35 points.

How can I prepare for an AP Physics Multiple Choice Question test?

To prepare for an AP Physics Multiple Choice Question test, it is important to review and understand the key concepts and principles covered in the course. Practice tests and questions can also be helpful in familiarizing yourself with the format and types of questions that may be asked. Additionally, attending review sessions or seeking help from a tutor can also aid in preparation.

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