Acceleration Time Pulley
1. **Problem statement:**
A particle of mass $m_1$ lies on a smooth horizontal table connected by a light inextensible string over a smooth fixed pulley to a freely hanging particle of mass $m_2$. Initially, the system is at rest with $m_1$ at a distance $d$ from the edge of the table. We need to show that the acceleration of the system is $$a=\frac{m_2 g}{m_1 + m_2}$$ and the time taken for $m_1$ to reach the edge of the table is $$t=\sqrt{\frac{2 d (m_1 + m_2)}{m_2 g}}.$$
2. **Set up the forces and equations:**
- Let the acceleration of $m_1$ towards the pulley be $a$.
- Since the string is inextensible, $m_2$ moves downward with acceleration $a$.
- Tension in the string is $T$.
3. **Apply Newton's second law to $m_1$ (horizontal motion):**
$$T = m_1 a$$
4. **Apply Newton's second law to $m_2$ (vertical motion):**
$$m_2 g - T = m_2 a$$
5. **Solve the system of equations:**
From step 3, $T = m_1 a$.
Substitute into step 4:
$$m_2 g - m_1 a = m_2 a$$
Rearranged:
$$m_2 g = m_1 a + m_2 a = (m_1 + m_2) a$$
Therefore,
$$a = \frac{m_2 g}{m_1 + m_2}$$
6. **Find the time $t$ for $m_1$ to reach the edge:**
- Initial velocity $u = 0$ (system starts from rest).
- Distance to cover $s = d$.
- Acceleration $a$ as above.
Using the equation of motion:
$$s = ut + \frac{1}{2} a t^2$$
Substitute values:
$$d = 0 + \frac{1}{2} a t^2 = \frac{1}{2} \cdot \frac{m_2 g}{m_1 + m_2} t^2$$
Solve for $t^2$:
$$t^2 = \frac{2 d (m_1 + m_2)}{m_2 g}$$
Hence,
$$t = \sqrt{\frac{2 d (m_1 + m_2)}{m_2 g}}$$
**Final answers:**
- Acceleration: $$a = \frac{m_2 g}{m_1 + m_2}$$
- Time to reach edge: $$t = \sqrt{\frac{2 d (m_1 + m_2)}{m_2 g}}$$