Q. No.A bullet hits a block kept at rest on a smooth horizontal surface and gets embedded into it. Which of the following does not change?
| 1. | linear momentum of the block |
| 2. | kinetic energy of the block |
| 3. | gravitational potential energy of the block |
| 4. | temperature of the block |
| 1. | \(\dfrac{m'}{m}=\dfrac{1}{10}\) | 2. | \(\dfrac{m'}{m}=\dfrac{1}{9}\) |
| 3. | \(\dfrac{m'}{m}=\dfrac{1}{8}\) | 4. | \(\dfrac{m'}{m}=\dfrac{1}{2}\) |
1. \(3:1\)
2. \(1:4\)
3. \(1:1\)
4. \(1:3\)
| 1. | 4.9 J | 2. | 9.8 J |
| 3. | 14.7 | 4. | 19.6 J |
1. \(46\)
2. \(384\)
3. \(192\)
4. \(768\)
Body \(\mathrm{A}\) of mass \(4m\) moving with speed \(u\) collides with another body \(\mathrm{B}\) of mass \(2m\) at rest. The collision is head-on and elastic in nature. After the collision, the fraction of energy lost by the colliding body \(\mathrm{A}\) is:
| 1. | \(\dfrac{5}{9}\) | 2. | \(\dfrac{1}{9}\) |
| 3. | \(\dfrac{8}{9}\) | 4. | \(\dfrac{4}{9}\) |
| 1. | \(v\left[\dfrac{mM}{(k(m+M)}\right]^{1/2}\) | 2. | \(v\left[\dfrac{mM}{(k(m-M)}\right]^{1/2}\) |
| 3. | \(\left[\dfrac{vkmM}{m+M}\right]^{1/2}\) | 4. | \(\left[\dfrac{vkmM}{m-M}\right]^{1/2}\) |
An electron collides with a free molecule initially in its ground state. The collision leaves the molecule in an excited state that is metastable and does not decay to the ground state by radiation. Let \(K\) be the sum of the initial kinetic energies of the electron and the molecule, and \(\vec{P}\) be the sum of their initial momenta. Let \(K'\) and \(\vec{P}'\) represent the same physical quantities after the collision. Then:
| 1. | \(K=K',~~\vec{P}=\vec{P}'\) |
| 2. | \(K'<K,~~\vec{P}'=\vec{P}\) |
| 3. | \(K=K',~~\vec{P}\neq\vec{P}'\) |
| 4. | \(K'<K,~~\vec{P}'\neq\vec{P}\) |
Particle \(A\) of mass \(m_1\) moving with velocity \((\hat{{i}}+\hat{{j}})~\text{ms}^{-1}\) collides with another particle \(B\) of mass \(m_2\) which is at rest initially. Let \(\vec{v}_1\) and \(\vec{v}_2\) be the velocities of particles \(A\) and \(B\) after collision respectively. If \(m_1=2m_2\) and after collision \(\vec{v}_1=\left(\hat{{i}}-\hat{{j}}\right)~\text{ms}^{-1}\) then the final velocity of the particle \(B\) is:
1. \(2\hat{i}+\hat{j}\)
2. \(2\hat{i}-\hat{j}\)
3. \(4\hat{j}\)
4. \(-4\hat{i}\)
In an inelastic collision:
| 1. | the initial kinetic energy is equal to the final kinetic energy. |
| 2. | the final kinetic energy is less than the initial kinetic energy. |
| 3. | the kinetic energy remains constant. |
| 4. | the kinetic energy first increases and then decreases. |
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