A small rock is thrown vertically upward with a speed of 22.0 m/s from the edge of the roof of a 30.0-m-tall building. The rock doesn't hit the building on its way back down and lands on the street below. Ignore air resistance. (a) What is the speed of the rock just before it hits the street?

Video transcript

So in this problem the stone is stone vertically upward with a speed of 10 m per second. From the top of the pipe. 15 m resistance is building. Stone strikes the ground. Delta H is equal to negative. Start from the top of the end at the bottom have a ball which is thrown with an initial velocity of 10 m seven awesome parabolic pad, Final Velocity which is less than zero. Now in free fall that the acceleration is the acceleration due to gravity 9 21. So we can start off by solving this problem by recalling economic equations. The FBI plus 18. The second one, delta X equals two B I C plus 1.5 squared 3rd 1. The square was the iceberg was to a we have a value of acceleration G. We have the initial velocity, we have delta H, which is simply delta acts there as they're both distances. We want to find VF. So among these equations, you can see that BF is most readily obtained equation three. So using three, you can directly solve the just taking the square but the other side, let me take this where we need to remember that there has to be plus or minus. Yeah, I squared plus two G. In this case delta H. Now from the diagram we can see that since it's going in the downward direction B F is less than zero. So we're only going to take this negative so we can make the direct substitution for the F as negative square roots BI was just 10 m/s Squared plus two times. Never mind one seven squared Times. Delta just negative BF surround equal to 32. m for second answer choice. B. Is it a speed it is actually positive. Have a great day.