Stones being dropped and thrown from building

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A stone is dropped from a building and a second stone is thrown downwards 1.90 seconds later, both landing simultaneously. The discussion involves calculating the time it takes for the first stone to reach the ground, the height of the building, and the speeds of both stones just before impact. Participants suggest using kinematic equations to solve for these variables, emphasizing the importance of understanding the effects of gravity and initial velocity. The conversation highlights the need for clear problem statements and adherence to forum rules for effective assistance. Properly applying physics principles will yield the required answers for the homework problem.
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Homework Statement


A stone is dropped from the roof of a building; 1.90 s after that, a second stone is thrown straight down with an initial speed of 29.0 m/s, and the two stones land at the same time.
a. How long did it take the first stone to reach the ground?

b. How high is the building?

c. What are the speeds of the two stones just before they hit the ground?


Homework Equations





The Attempt at a Solution

 
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To save time, and to be polite, Physics Forums should define something like: "Standard Response 001" being something like "Welcome to PF. Please observe the PF rules for posting, then we'd be happy to help."
 
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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