physics (tension in strin and acceleration of syst
posted by ahsan asghar on .
two bodies of 9kg and 5.7kg are attached with ends of a string which passes over a pulley so that both bodies move vertically starting from rest at equal heights,lighter body hits pulley in 1.2sec.find length of string and speed with which it hits pulley.diameter of pulley is 14cm

ans (3.608m,3.388m\sec)

a stone is dropped from the top of a tower .in the last second of its motion it travels a distance of 44,1m.find(a)height of tower .(b)velocity while hitting the ground.

Let H be the tower heiight and g the acceleration of gravity (9.8 m/s^2). Let t be the time it takes to fall the full tower height. Here is what you know:
H = (g/2) t^2
H44.1 = (g/2)(t1)^2
Solve those two equations TOGETHER for the height H. It is easiest to solve for t first
44.1 = (g/2)*[t^2  t^2 + 2t 1)
= 4.9 [2t  1)
2t 1 = 9
t = 5 seconds
H = 4.9*25 = 122.5 m
(b) Vfinal^2 = 2 g H