Physics Question Please Reply

[ORELL]

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How Long Does It Take For A 33 Rev/min Record To Rotate Once At Constant Speed.
Answer Should Be Only In Seconds

 

[Brick Walls]

like a lot of physics questions, this is basically dealing with the ability to rearrange an equation.
so...33rev/min...since we need the answer in seconds, lets convert minutes to seconds: 33 rev/60 seconds
so, we know that this record will undergo 33 revolutions in 60 seconds, and we need to find out how long will it take for it to revolve once.

you can't use calculators on MCAT, so I would round the 33 to 30...its easier to the math with 30 than with 33.
now, the equation is: 30 rev/ 60 sec

if you reduce this you will get: 1 rev/ 2 sec

The record will revolve once every 2 seconds...keep in mind that we rounded the 33 to 30, so the answer you are looking for is somewhere near 2 (probably a little less than 2).

 

[ORELL]

Thats what i did and got 1.81 and the choices were
0.033 , 0.29, 2.66 and 3.33
and now what??????

 

[iA-MD2013]

Yeah, I think you and Brick Walls are right. 1.81s should be the right answer. where is physics junkie when you need him 😉

 

[Brick Walls]

weird...i dont know...if this happens on the MCAT...just choose "C"..j/k

 

[tncekm]

Its definitely 1.81s.

33 rev / min can be rearranged to 1 min/ 33 rev x 60s/min = 60/33 s/rev = 1.81 s/rev.

C is definitely the best approximation, but the answer choices are definitely wrong.

 

[RSAgator]

only thing i could think is either the answer choices are wrong or you wrote the question wrong. Maybe it's asking the distance per second or something? If you divide by 2pi u get approximately .29 i think