a body is thrown vertically up with a velocity u.It passes a point at h height h above the ground at time t1 while going up and time t2 whil falling down .then the relation between t1 ,t2 nad h is
Dear Shivam, as far as I remember this question it asks to find the relation between t1, t2 and u (not h). If you want to find relation between t1, t2 and h then you can relate equation 1 and equation 4. I am providing you with the complete answer.
When a body, that is thrown vertically with velocity u, reaches a vertical distance h from ground at time t1,
Thus, we will have, h = u×t1 - (1/2)g×t1^2--- (1)
If H is maximum the height it reaches with time T, then we will have
H = u2 / (2g) --- (2)
T = u/g ............................... (3)
During descending, if the object crosses the same spot which is at a height h above the ground, then the vertical distance travelled during ascending will be ( H-h ). Thus -
(H - h) = (1/2) gt^2 ---(4)
where t is the time taken to travel from highest point to the distance (H-h) .
If t2 is the time for the object, when it starts from the ground, and reaches maximum height and again crosses the spot which is at a distance h from ground, then we have,
t = (t2 - T ) --- (5)
Writing Eqn.(4) by substituting for H, h and t using respective eqns. (2), (1), (3) and (5)
[ u2 / (2g) ] - u×t1 + (1/2)g×t12 = (1/2)g [ t^2 - (u/g) ]^2 --- (6)
After simplifying equation (6), we will get,
t1 + t2 = 2u/g
All the best
Hope this helps