InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Prove that if a body is thrown vertically upwards, then the time of ascent is equal to the time of descent. |
|
Answer» Let, u = Initial velocity v = Final velocity h = Height attained a = acceleration t = time Ascent: Ball thrown upward with velocity u. So, v = 0 at maximum height h. Also, a = -g Now, using v = u + at 0 = u - gta ta = \(\frac{u}{g}\).......................1 Where ta = time of ascent Also, by using V2 = U2 + 2as 0 = u2 - 2gh u = \(\sqrt {2gh}\).............2 From equations 1 and 2, we get, ta = \(\sqrt \frac{2h}{g}\)..........A Descent: Ball comes down from height h. So, u = 0 and a = g. So, using v = u + at v = gtd ….......3 Where td = Time of descent Now, using v2 = u2 + 2as v2 = 0 + 2gh v = \(\sqrt {2gh}\)................4 From equations 3 and 4, we see that, td = \(\sqrt \frac{2h}{g}\)..........B From equations A and B, we see that, ta = td |
|