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Physics: kinematics in one dimension.
Casually Hardcore
Once an Asshole. Trying to be better.Registered User regular
Once an Asshole. Trying to be better.Registered User regular
Okay, here's a quick question. I'm pretty sure my logic is correct, but I just need to be certain.
The question in the book is basically something like this:
"A rocket is launched straight up with a constant acceleration. After 16 seconds the rocket is turned off. After 20 seconds, the rocket is now at 5100m. What is the acceleration during the first 16 seconds of the rocket?"
I'm not concerned about the math part of this problem, but problem is with my logic behind my answer.
Basically, what I did is draw two motion diagram. One with the rocket on, and the other with the rocket off.
Then, I realized that I know the acceleration, the change in time, and a final position for when the rocket is off.
Knowing those variables, I set my initial position as '0m' and solved for my initial velocity.
Now this is where my doubts come in. Can I set my initial position as 0m, even though it isn't really 0m when the rocket is turned off?
The question in the book is basically something like this:
"A rocket is launched straight up with a constant acceleration. After 16 seconds the rocket is turned off. After 20 seconds, the rocket is now at 5100m. What is the acceleration during the first 16 seconds of the rocket?"
I'm not concerned about the math part of this problem, but problem is with my logic behind my answer.
Basically, what I did is draw two motion diagram. One with the rocket on, and the other with the rocket off.
Then, I realized that I know the acceleration, the change in time, and a final position for when the rocket is off.
Knowing those variables, I set my initial position as '0m' and solved for my initial velocity.
Now this is where my doubts come in. Can I set my initial position as 0m, even though it isn't really 0m when the rocket is turned off?
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It seems like making your initial position at t(16) 0 and solving for intial velocity would work, but the 5100 is your only distance number so you'd need some other variables.
that's why we call it the struggle, you're supposed to sweat
Using the equation distance=initial position + (initial velocity)*time + (1/2)(acceleration)*time^2, solve for 'a'.
GT: Tanky the Tank
Black: 1377 6749 7425
Well, I was quickly summarizing the question from the book. This is what I did and my equation is:
5100m = 0 +Vi(4s) + (1/2)(g)(4.0s)^2
vi being my initial velocity.
Then I used the value of my initial velocity to find acceleration for the first 16 seconds by setting the initial velocity when the rocket is off, as my final velocity when the rocket is on.
Is my reasoning correct? I can't look up the answer.
duh
shadydentist's reasoning (which is really your reasoning) seems right to me
that's why we call it the struggle, you're supposed to sweat
Anyways, that really boosted my confidence. Thanks y'all.
F(orce) = m(ass) x a(ccel)
so
a = F/m.
A decrease in "m" makes "a" higher over time.