Help with Oscillation - Can't Figure Out the Answer!

[cupid.callin]

Homework Statement

Hi all

The Attempt at a Solution

#1
I can't understand what exactly oscillation is. I guessed a,b,c are correct but c is not the answer ... why?

#2
No idea.

#3
a, b ?

#4
i guessed its c,d ... but again i was wrong

#5
No idea, sorry :(

 

[ideasrule]

#1
I can't understand what exactly oscillation is. I guessed a,b,c are correct but c is not the answer ... why?

Oscillatory motion simply means the mass moves back and forth from one position to another. It doesn't have to be periodic: it could complete the first cycle in 1 second and the second cycle in 4, for example, even if it moves between the same two points.

#2
No idea.

Here's a hint: in a non-inertial frame, everything feels a force of ma. This is exactly equivalent to a gravitational field of strength "a"--in fact, Einstein's equivalence principle says there's no way to differentiate the two. So think about a spring hanging downwards in Earth's gravitational field; it will behave in exactly the same way as a spring hanging downwards in a room accelerating upwards at "g".

#3
a, b ?

No, b is not correct. Imagine a spring going through one complete cycle, and see which of the quantities remain positive throughout the cycle. Remember that if the vectors are parallel, the dot product is positive; if they're antiparallel, it's negative.

#4
i guessed its c,d ... but again i was wrong

c and d are definitely correct. There's one more option that's also right.

#5
No idea, sorry :(

Have you learned about resonance?

 

[gneill]

#4 is a bit problematical if one considers the effects of the Earth's rotation on a falling mass when the tunnel is not placed along the rotational axis. Perhaps they should have specified a non-rotating Earth.

 

[cupid.callin]

hi guys
sorry for late reply

#3
it should be a,b because before this question was a question asking about negative quantities. whose answer was c,d
and v is always in direction of r ... i guess

#4
@gniell
but still it will look like shm for someone on Earth even if tunnel is not along rotation axis
it might be parabolic or someone not rotating with earth

@ideasrule
i know you mean acd but its also wrong
answer includes b