Banner 0
Banner 1
Banner 2
Banner 3
Banner 4
Banner 5
Banner 6

Q.

A rod AC Of length l and mass m is kept on a horizontal smooth plane. It is free to rotate and move. A particle of same mass m moving on the plane with velocity v strikes rod at point B making angle 370  with the rod. The collision is elastic. After collision:

Question Image

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away
An Intiative by Sri Chaitanya

a

The angular velocity of the rod will be  72V55l

b

The centre of the rod will travel a distance  πl3 in the time in which it makes half rotation.

c

Impulse of the impact force is  24mV55

d

The centre of the rod will travel a distance  πl8 in the time in which it makes 1/4th rotation

answer is A, B, C.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

detailed_solution_thumbnail

The ball has V’ component of its velocity perpendicular to the length of the rod immediately after the collision. 

u is the velocity of CM of the rod and ω is angular velocity of the rod just after collision.  

The ball strikes the rod with speed v  cos  530 in perpendicular direction and its component along the length of the rod after the collision is unchanged.

Using for the point of collision.

Velocity of separation = Velocity of approach

Question Image

3V5=(ωl4+u)+V' ....................(1)

Conserving linear momentum (of rod + particle) in the direction   to the rod,
mV35=mumV' ....................(2) 0=0+[ul4ml212ω]u=ωl3 u=24V55,  W=72V55l ....................(3)

Time taken to rotate by π angle,  t=πω
 

Question Image


In the same time, distance travelled   =u2  t=πl3
Using angular impulse-angular momentum equation,
  Ndtl4=ml24.72V55lω {    Ndtl4=24mV55}

  [using impulse-momentum equation on the rod    Ndt=mu=24mV55 ]

Watch 3-min video & get full concept clarity

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon
A rod AC Of length l and mass m is kept on a horizontal smooth plane. It is free to rotate and move. A particle of same mass m moving on the plane with velocity v strikes rod at point B making angle 370  with the rod. The collision is elastic. After collision: