A ball is dropped from a high rise platform at t=0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with a speed v. The two balls meet at t=18s. What is the value of v? (take g=10m/s2)
75m/s
55m/s
40m/s
60m/s
As we learnt in
2nd equation or Position- time equation -
Displacement
Initial velocity
acceleration
time
-
Distance moved in 18 sec by first half,
Distance moved in 12 sec by second half,
1620 = 12v + 5 x 144
Option 1)
75m/s
Correct
Option 2)
55m/s
Incorrect
Option 3)
40m/s
Incorrect
Option 4)
60m/s
Incorrect