Tag: momentum

Questions Related to momentum

A uniform rod AB of mass $3m$ and length $2l$ is lying at rest on a smooth horizontal table with a smooth vertical axis through the end $A$ . A particle of mass $2m$ moves with speed $2u$ across the table and strikes the rod at its mid point $C$. If the impact is perfectly elastic , then find the speed of the particle after impact if it strikes the rod normally 

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. $\dfrac{7u}{3}$

  2. $\dfrac{2u}{3}$

  3. $\dfrac{u}{3}$

  4. $\dfrac{4u}{3}$

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Correct Option: C

A body falls from height 20 m.If coefficient of restitution 1/2. The time interval between starting point and second bounce is $\left( {g = 10\;m{s^{ - 2}}} \right)$

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. 1 s

  2. 2 s

  3. 3 s

  4. 4 s

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Correct Option: C

A disc of mass $100g$ and radius $10cm$ has a projection on its circumference. The mass of projection is negligible. A $20g$ bit of putty moving tangential to the disc with a velocity of $5m{s}^{-1}$ strikes the projection and sticks to it. The angular velocity of disc is

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. $14.29rad{s}^{-1}$

  2. $17.3rad{s}^{-1}$

  3. $12.4rad{s}^{-1}$

  4. $9.82rad{s}^{-1}$

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Correct Option: A

Two spheres $A$ and $B$ of masses $m _1$ and $m _2$ respectively collide. $A$ is at rest initially and $B$ is moving with velocity $v$ along x-axis. After collision $B$ has a velocity $\cfrac{v}{2}$ in a direction perpendicular to the original direction. The mass $A$ moves after collision in the direction

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. Same as that of $B$

  2. Opposite to that of $B$

  3. $\theta=\tan^{-1}{(1/2)}$ to the x-axis

  4. $\theta=\tan^{-1}{(-1/2)}$ to the x-axis

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Correct Option: A

A rod of length on two metal pads of same height from a height $h$. The coefficients of restitution of the metal pads are ${e} _{1}$ and ${e} _{2}$ (${e} _{1}> {e} _{2}$). The angular velocity of the rod after it recoils is

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. $\cfrac { { e } _{ 1 } }{ { e } _{ 2 } } l\sqrt { 2gh } $

  2. $\cfrac { { e } _{ 1 }-{ e } _{ 2 } }{ l } \sqrt { 2gh } $

  3. $\cfrac { { e } _{ 1 }+1 }{ { e } _{ 2 }+1 } \sqrt { 2gh } $

  4. $\cfrac { { e } _{ 1 }+1 }{ { e } _{ 2 }-1 } \sqrt { 2gh } $

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Correct Option: C

In a collision between two solid spheres. velocity of separation along the line of impact (assume no external forces act on the system of two spheres during impact):

physics momentum collision of two rigid bodies energy and collisions understanding collisions

  1. Cannot be greater than velocity of approach

  2. Cannot be less than velocity of approach

  3. Cannot be equal to velocity of approach

  4. none of these

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Correct Option: A
Explanation:

$\begin{array}{l} e=\dfrac { { volume\, \, of\, \, sep } }{ { volume\, \, of\, \, app } }  \ 0<e<1 \ \Rightarrow Volume\, \, \, of\, \, sep<volume\, \, of\, \, app \end{array}$

$\therefore $ Option $A$ is correct.

When a ball collides head-on and elastically with an identical ball on a horizontal frictionless surface,comes to rest while the second one moves with the same velocity as that of the first ball before coillision . 

modelling collisions collisions momentum work, energy and power physics

  1. Can be derived by using momentum conservation alone.

  2. Can be derived by using energy conservation alone

  3. cannot be derived by using any to the two conservation principles.

  4. Can be derived by using both conservation of energy and momentum

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Correct Option: A

A ball 'A' of mass 100 gm moving at 2m/s collides with another identical ball 'B' at 3m/s along the same line. There is no loss in energy collision. then, the speed of the balls 'A' and 'B' after the collision are ?

modelling collisions collisions momentum work, energy and power physics

  1. 1m/s and 4m/s

  2. 2m/s and 3 m/s

  3. 3 m/s and 2 m/ s

  4. 2.5 m/s and 2.5 m/s

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Correct Option: B

Two bodies A and B of masses 5 kg and 10 kg moving in free space in opposite directions with velocity form for second and 0.5 m per second respectively undergo a head on collision the force f of their mutual interaction varies with time T according to the given graph what can you conclude from the given information

modelling collisions collisions momentum work, energy and power physics

  1. Period of Di formation is 0.2 second

  2. Coefficient of restitution is 0.5

  3. Body 0.5 m per second in the original direction

  4. Body be will 1.75 M per second in the reverse direction

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Correct Option: A

A solid cylinder of mass 'M' and radius 'R' is rotating along its axis with angular velocity $\omega $ without friction. A particle of mass 'm' moving with velocity v collide against the cylinder and sticks to its rim. After the impact calculate angular velocity of cylinder.

modelling collisions collisions momentum work, energy and power physics

  1. $\cfrac { I+R\omega }{ I+m{ R }^{ 2 } } $

  2. $\cfrac { mvR+IR }{ I+m{ R }^{ 2 } } $

  3. $\cfrac { I\omega +mvR }{ I+m{ R }^{ 2 } }$

  4. $\cfrac { I\omega +mR }{ I+mv{ R }^{ 2 } } $

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Correct Option: C