Calculate the common velocity after the impact. 8. State two evidences that matter is made up of small particles

Mass of arrow, $m_1 = 100 \text{ g} = 0.1 \text{ kg}$
Mass of block of wood, $m_2 = 400 \text{ g} = 0.4 \text{ kg}$
Initial velocity of arrow, $u_1 = 15 \text{ m/s}$
Initial velocity of block of wood, $u_2 = 0 \text{ m/s}$ (since it is at rest)
Common final velocity, $V = ?$

The total momentum before impact equals the total momentum after impact.

The common velocity after impact is $\boxed{\text{3.0 m/s}}$.

8. State two evidences that matter is made up of small particles

Two evidences that matter is made up of small particles are:

• Diffusion: The spreading out of particles from a region of higher concentration to a region of lower concentration, such as the smell of perfume spreading in a room.
• Brownian motion: The random movement of microscopic particles suspended in a fluid (liquid or gas) due to their collision with the fast-moving atoms or molecules in the fluid.

9. Distinguish between conduction and convection

• Conduction is the transfer of heat through direct contact between particles, without the bulk movement of the material itself.
• Convection is the transfer of heat through the movement of fluids (liquids or gases) from hotter regions to colder regions.