Does anyone know what I’ve done wrong? My answer isn’t in the options
#suvat
neon patio
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Does anyone know what I’ve done wrong? My answer isn’t in the options
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amber jackal
Does anyone know what I’ve done wrong? My answer isn’t in the options
Suppose the initial point of the piece where it slopes down is (t1, v1) and the second is (t2, v2). What will the equation of this piece be?
neon patio
Suppose the initial point of the piece where it slopes down is (t1, v1) and the ...
do u mean the points (80,20) and (180,-10)?
amber jackal
do u mean the points (80,20) and (180,-10)?
Yes. Let's approach this generally for now, though.
neon patio
y=((v2-v1)/(t2-t1))x + c
should i find c aswell?
c= v2-(((v2-v1)/(t2-t1))t2
y=((v2-v1)/(t2-t1))x + v2-(((v2-v1)/(t2-t1))t2 that looks complicated
amber jackal
y=((v2-v1)/(t2-t1))x + c
Our variables are t and v, not x and y. So:
v = v1 + (v2 - v1)(t - t1)/(t2 - t1)
Now, we want v = 0. So:
v1 + (v2 - v1)(t - t1)/(t2 - t1) = 0
Solve this for t.
neon patio
t=(t2v1-t1v2)/(v1-v2)
amber jackal
Right, nice!
So, now you can substitute the values.
Note that you can divide the numerator and denominator by v1 v2, obtaining an even nicer expression:
t = (t2/v2 - t1/v1)/(1/v2 - 1/v1) = Δ(t/v)/Δ(1/v)
neon patio
im not sure why but im still not getting an answer
amber jackal
im not sure why but im still not getting an answer
What did you get?
neon patio
44..
amber jackal
No, that's not correct. Can you show your calculation?
neon patio
I just tried it again i got 357/3
neon patio
wait is it 440/3
neon patio
147 seconds
amber jackal
Great!
amber jackal
Ah, I see.
You're welcome!
neon patio
this would also work if I did it using the specific values from the start right?
amber jackal
Yes. However, I advice against it.
It's better to solve physics and chemistry problems generally, if possible.
That is the usual approach, after all: you derive the formula, then substitute the values.
neon patio
okay so steps are
- find the general equation for velocity in terms of v and t
- v=0 solve for t
- sub in the values to get t
amber jackal
Yup.
neon patio
okay thank you :)