Question

do now / review worksheet
bouncing balls lab — momentum, collisions & energy
bounce height visual
momentum diagram

1. what is momentum? what two variables determine it?
2. why does dropping height matter for velocity before impact?
3. list the two types of collisions you learned.
4. explain the difference between elastic and inelastic collisions.
5. which ball bounced highest in your lab and why?
6. calculate velocity before impact for a 0.12 kg ball dropped from 1 m.

Explanation:

Step1: Apply conservation of energy

Gravitational potential energy converts to kinetic energy: $mgh = \frac{1}{2}mv^2$. Mass cancels out.

Step2: Solve for velocity

Rearrange formula: $v = \sqrt{2gh}$. Substitute $g=9.8\,\text{m/s}^2$, $h=1\,\text{m}$.

Step3: Calculate the value

$v = \sqrt{2 \times 9.8 \times 1} = \sqrt{19.6} \approx 4.43\,\text{m/s}$.

1. Momentum is mass in motion, determined by mass and velocity.
2. Higher height means more gravitational potential energy, converting to greater kinetic energy (and thus velocity) before impact.
3. Elastic collisions and inelastic collisions.
4. Elastic collisions conserve both momentum and kinetic energy; inelastic collisions conserve momentum but not kinetic energy (some energy is lost).
5. Depends on lab data—typically a more elastic ball (e.g., a hard rubber ball) bounces highest because less kinetic energy is lost as heat/deformation.

Answer:

Approximately 4.43 m/s