Physics · Forces and motion
Masses and Springs (Hooke's Law)
A spring stretches more when you hang a heavier mass on it. How much it stretches depends on how stiff the spring is.
- Stretch at rest (mg ÷ k)
- 24.5 cm
- Spring force now (k × x)
- 13.8 N
- Weight (m × g)
- 9.8 N
- Time period T
- 0.99 s
Damping (air resistance)
Try this
- Double the mass. Does the stretch double?
- Use a stiffer spring with the same mass. What happens to the stretch and to the bouncing?
- Pull the mass down and let go with damping off. Does the time for one bounce depend on how far you pulled?
Key ideas
- Hooke's law: force F = k × x, where x is the stretch and k is the spring constant.
- At rest, the spring's upward force equals the weight: k × x = m × g.
- Time period of bouncing T = 2π√(m ÷ k): heavier masses bounce more slowly, stiffer springs faster.