TBR test 1 phys sciences q 1

[2010premed]

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If the pendulum completes one full cycle of motion in less time than the turntable, what change would produce equal periods for both systems?

• Suspending the pendulum in a less viscous medium than air</SPAN>
• Moving the marker closer to the center of the turntable

</SPAN>
Answer is B

My question is, in the exp it says that “Suspending the pendulum in a medium that is less viscous than air increases the velocity of the swinging ball at any point in its arc (except rest),” what equation did this come from? Also, how does “Moving the weighted marker closer to the center of the turntable causes the angular speed of the turntable to increase”?

 

[TieuBachHo]

My question is, in the exp it says that “Suspending the pendulum in a medium that is less viscous than air increases the velocity of the swinging ball at any point in its arc (except rest),” what equation did this come from? Also, how does “Moving the weighted marker closer to the center of the turntable causes the angular speed of the turntable to increase”?

1) The higher the viscousity, the higher the friction/drag force.
2) What is the equation for angular velocity? Something has to do with the radius right?

 

[2010premed]

ah yes, it's w = v/r thanks =)

I guess what confuses me in this passage is the marker... and also, I thought I read in BR that angular velocity does not change on a rotating object?

 

[2010premed]

I just looked at the explanation again and it says that it's b/c of conservation of angular momentum??

 

[fizzgig]

if you have a weight rotating and you bring it in closer it'll go faster. think of a figure skater.