Simple (was thought to be) Gravity Question

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The discussion revolves around calculating the initial velocity of a ball rolling up a slope, given its maximum displacement and time. The user initially applies the formula d=vt, leading to an incorrect initial velocity of 0.722 m/s, while the correct answer is 1.4 m/s. The conversation highlights the need to consider acceleration due to gravity, prompting the use of the formula d=Vit + 0.5at^2 instead. The user also expresses concern about posting multiple questions in separate threads, seeking guidance on forum etiquette. Overall, the thread emphasizes the importance of understanding kinematic equations in physics.
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[SOLVED] Simple (was thought to be) Gravity Question

Homework Statement


A ball is rolled up a constant slope. After 3.6 s it reaches its maximum displacement of 2.6m, and then begins to roll back down. What was the initial velocity of the ball when it started up the slope?


Homework Equations





The Attempt at a Solution


i know that d=vt of course, but, 2.6=v(3.6), and V would equal 2.6 divided by 3.6 which is .722, and the answer in the key is 1.4m/s?? In all likelihood, its probably something extremely obvious?
 
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You can't use d=vt because there is an acceleration due to gravity
use d=vt-.5at^2
 
you mean d=Vit+.5at^2, emphasis on plus sign?
 
well yes, in this case the acceleration is negative but the formula you gave is the more general form.
 
grantP said:
you mean d=Vit+.5at^2, emphasis on plus sign?

edit: thanks by the way, the question screwed me up w/ the word constant, plus I am taking my very first physics course (phys. 11)----one more question is i might have quite a few questions today...will mods get mad for me making quite a few threads? (maybe 10?)
 
If they're the same types of problems I'd just stick them in the same thread.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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