Hi guys, My professor showed us in class how to find the final velocity of an object as it hits the the atmosphere of earth(Rf=6.37e6) and I think he might have made a mistake. I have been trying to solve the same problem but I get different answer than the one my professor showed in class. The Ri=6.37e6 + 10^5. Vi=0. The way I solved it - 1/2mvf^2 −GmM/Rf=−GmM/Ri (I canceled out the m) My answer is 695 m/s. It seems like my professor didn't cancel out the first m and he got 435 or something around that number. I wonder if there is a reason why he didn't cancel the first m, or rather he just forgot to do so. Thank you so much!