So the stupid spring question....
It states "the ball and spring come to rest when they are at a distance of 0.50 m below the uncompressed position of the spring."
To me, that sounds as if the ball and spring have stopped oscillating. Thus the forces are balanced, and mg = kx, and thus k = 39.2 N/m.
If it means the lowest point that the ball reaches, then it should have specified MOMENTARILY at rest. In which case you use an energy approach and you end up with k = 392 N/m. But the lack of the word MOMENTARILY changes the question completely.
Not to mention the rest of the question. Are we to assume that now the ball has stuck to the spring and is undergoing an oscillating motion? And we are to analyse the motion of the ball after it has stuck, disregarding the first part of the ball's motion? Because then the question makes sense. BUT NO WHERE DOES IT SAY TO DO THAT!
Rant over, sorry guys.
Difficultiy, confusion or frustration should never be confused with stupidity.
Spring question
(a)
k = 2mg∆h/(∆x)^2
= 2 • 2 • 9.8 • 2.5/ (0.5)^2
= 98/ 0.25
k = 392 N m^-1 (Q.E.D).
(b)
Common answer (reasonable) was 9.8 m s^-2 this is wrong however, actual and final answer is 0 m s^-2 since acceleration-mass system when max speed is reach is 0.
(c)
∆x for max speed. Max speed occurs at midpoint of compression, therefore, ∆x/2 = 0.5/2 = 0.25 m
PD was given so was wavelength, solve for n (n=4.0082),
Speaker
Wavelength = 1m (v=fwavlength).
Transmission questions were misleading since current in lines in normally what you would calculate first and then progress to the power loss questions. Anyhow, this would be answered terrible, overall, harder than last years as expected (first year study design) is always easier, but nevertheless 2018 class is all in this together.
Love, the zero gravity questions
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Topic: Physics: Discussion, Questions & Potential Solutions (Read 54285 times)