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a body of mass m collides with a wall (angle between ball and wall is 60 degrees) if the speed (v) doesnt change when rebounding...............find its change in momentum......HELP PLS!!!!!!!!

Shivam Bhagat , 13 Years ago
Grade 9
anser 3 Answers
Ashwin Muralidharan IIT Madras

Last Activity: 13 Years ago

No change in speed.

Only the direction of velocity changes.

 

So collides at angle 60 deg to wall, and also rebounds at angle 60 deg to wall, like a "V".

 

So change in momentum = 2vsin60*m = √3mv. (only along the vertical direction - momentum doesn't change along the horizontal direction).

 

Hope that helps.

 

Best Regards,

Ashwin (IIT Madras).

Archit Bhatt

Last Activity: 13 Years ago

break d momentum in components....at horizontal mv cos 60 at vertical mv sin 60....the chnge in momnetum will be 0 in vertical direction but it will chnge its path after collision in horizonntal direction....so change is mv/2 -(-mv/2) = mv

Menka Malguri

Last Activity: 13 Years ago

When the ball of mass m collides with the ball with velocity v1 making angle 30° with the normal to the wall,it rebounds with velocity v2 at an angle 30° to the normal on the wall (angle between the ball and the normal=90°-angle between the wall and the ball).Here,the speedc v1 and v2 are same but the directions are different,so the velocities are different.

now,change in momentum would be

Δp=mv1-mv2

Δp=m(v1-v2)

Subtracting the two velocities vectorially,we get,

Δp=m[√(v12+v22-2v1v2cosθ)],here θ is the angle between the two velocities.

Δp=m[√(v2+v2-2v2cos120°)]

Δp=m[√(2v2-2v2(-1/2))]

Δp=m[v√3]

so,the change in momentum is (mv√3).

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