# MCAT Physics Questions Help (Pakistan) (SHM-Related)



## coolboy_a35 (Jun 26, 2014)

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 _Note: SHM means Simple Harmon Motion._

Having difficulty solving the following few questions,

1) Total energy of a body executing SHM is directly proportional to,

A) Square root of amplitude.
B) The amplitude.
C) Reciprocal of amplitude
D) Square of amplitude.

2) For what displacement does the P.E become 1/4 of its maximum value?

A) x = x'
B) x = x'/2
C) x = x'/4
D) x = x(2)'/2

3) The projection of a particle moving in a circle with non-uniform speed executes,

A) SHM
B) Vibratory motion
C) No SHM
D) Both (B) and (C)

4) A cup of milk is placed in a microwave oven. Tell which statements is false (1) Milk will be heated up only (2) Cup will remain cool (3) Both cup and mild will get hot.

A) 1
B) 2
C) 3
D) None

5) The energy absorbed by a body is ________________ at resonance.

A) Maximum only
B) Minimum only
C) Maximum as well as minimum
D) Zero


Any help would be appreciated. Thanks.


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## Ujarsh (May 29, 2013)

1=d 2=b 3=c 4=c 5 =a. R these right answers? And what confusion u got solving these questions u can ask ..


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## coolboy_a35 (Jun 26, 2014)

1) I didn't know the relation between total energy and amplitude. Your answer is correct. 
2) How did you solve this? 
3) The answer is (d), according to the practice test answers. 
4) Shouldn't both the cup and milk get hot? How is this related to resonance? 
5)As I recall, resonance was the *gradual loss* of energy and amplitude with time. How and when is energy absorbed?


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## Ujarsh (May 29, 2013)

1) formula of total energy is given in a text book ;total energy=1/2kx^2 where x is amplitude.
2) as p.E=1/2kx^2 where x is displacement ..when we put x=x/2 p.E will become 1/4.
3) vibratory is to and fro motion about a mean position i got confused yes, then it can be vibratory as well.
4) in resonance k.e energy increases this is how temp increases of both milk and cup.
5) no,resonance is increase of energy and amplitude i think u are confusing it with damping.


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