KinematicsHard
Question
A ball is dropped from a bridge 122.5m high. After the ball has fallen for 2 second, a second ball is thrown straight down after it. what must be the velocity of second ball so that both the balls hit the surface of water at the same time?
Options
A.26.1m/s
B.9.8m/s
C.55.5m/s
D.49m/s
Solution
Time takn by the first object to reach the ground = t, so
122.5 = ut +
gt2
122.5 = × 10 × t2
⇒ t = 5 sec (approx)
Time to be taken by the second ball to reach the ground = 5 - 2 = 3 sec. Ifu be initial velocity then,
122.5 = u × 3 +gt3 = 3u + × 10 × 9
3u = 122.5 - 45 = 77.5
u = 26 (approx.)
122.5 = ut +
gt2122.5 =
× 10 × t2 ⇒ t = 5 sec (approx)
Time to be taken by the second ball to reach the ground = 5 - 2 = 3 sec. Ifu be initial velocity then,
122.5 = u × 3 +
gt3 = 3u + × 10 × 93u = 122.5 - 45 = 77.5
u = 26 (approx.)
Create a free account to view solution
View Solution FreeMore Kinematics Questions
Let and be the instantaneous velocity and acceleration respectively of a particle moving in a plane. The rate of change ...A particle is projected at angle 37o with the incline plane in upward direction with speed 10 m/s. The angle of incline ...A particle is projected at 60o to the horizontal with a kinetic energy K. The kinetic energy at the highest point is...A point moves with uniform acceleration and its initial speed and final speed are 1 m/s and 2 m/s respectively then, the...A particle is moving in a plane with velocity given by = u0î + (aωcosωt) ĵ , where î and ĵ...