Basic Maths and Units and DimensionsHard

Question

Block ′A′ is hanging from a vertical spring and is at rest. Block ′B′ strikes the block ′A′ with velocity ′v′ and sticks to it. Then the value of ′v′ for which the spring just attains natural length is:
             

Options

A.
B.
C.
D.none of these

Solution

           
The initial extension in spring is x0 =
Just after collision of B with A the speed of combined mass is  .
For the spring to just attain natural length the combined mass must rise up by x0 =  (sec fig.) and comes to rest.
Applying conservation of energy between initial and final states

Solving we get v = 

Create a free account to view solution

View Solution Free
Topic: Basic Maths and Units and Dimensions·Practice all Basic Maths and Units and Dimensions questions

More Basic Maths and Units and Dimensions Questions

A phonograph turn-table rotating at 78 rev/min slows down and stops in 30 sec after the motor in turned off. Then the re...A body has speed V, 2V and 3V in first 1/3 of distance S, seconds 1/3 of S and third 1/3 of S respectively. Its average ...On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground...An elevator and its load have a total mass of 800 kg. If the elevator, originally moving downward at 10 m/s, is brought ...If electronic charge e, electron mass m, speed of light in vacuum c and Planck′s constant h are taken as fundament...