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urp:physfreq
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urp:physfreq [2021-11-08] nerf_herder created |
urp:physfreq [2021-11-17] (current) nerf_herder |
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| string, frequency, antinodes: | string, frequency, antinodes: | ||
| - | Adjacent antinodes are separated by a distance of 20 cm and waves travel at a speed of 1200 cm/s along the string. What frequency is the string vibrating at? | ||
| Ends of a stretched string are called nodes, N. | Ends of a stretched string are called nodes, N. | ||
| Line 9: | Line 8: | ||
| full sine wave (2N) = wavelength | full sine wave (2N) = wavelength | ||
| - | wavelength = 40 cm | + | Example: |
| - | freq = v/wavelength, v = velocity of wave | + | Adjacent antinodes are separated by a distance of 20 cm and waves travel at a speed of 1200 cm/s along the string. |
| - | 1200/40 = 30 | + | What frequency is the string vibrating at? |
| + | wavelength = 40 cm | ||
| + | freq = v/wavelength, v = velocity of wave | ||
| + | 1200/40 = 30 | ||
| **Doppler effect** => F = Fo (v +/- vo) / (v +/- vs) | **Doppler effect** => F = Fo (v +/- vo) / (v +/- vs) | ||
| Line 19: | Line 21: | ||
| + | ====Spring and Lever==== | ||
| + | **Hooke's law** for springs: F=-kx, k=spring constant, x = displacement | ||
| + | |||
| + | Spring energy: | ||
| + | * potential energy: U = 1/2 kx², or | ||
| + | * P = mgh (at mass at a given height) | ||
| + | * kinetic energy: K = 1/2 mv² | ||
| + | |||
| + | conservation of energy: potential energy + kinetic energy = constant, for a system | ||
| + | |||
| + | **Fulcrum**: t = r * f (torque = radius * force) | ||
| + | just add the torques for multiple objects on one side of a fulcrum | ||
| + | |||
| + | ====SHM - Simple Harmonic Motion==== | ||
| + | F = ma => ma = -kx | ||
| + | |||
| + | angular frequency ω = √(k/m) | ||
| + | |||
| + | period of oscillation T = 2π √(m/k) (horizontal or vertical springs) | ||
| + | |||
| + | In a vertical spring, the weight Mg of the body produces an initial elongation to equilibrium, such that Mg − kyₒ = 0. | ||
| + | |||
| + | If y is the displacement from this equilibrium position the total restoring force will be Mg − k(yₒ + y) = −ky | ||
| + | |||
| + | ---------- | ||
| + | Back to the [[Physics]] page or the [[00_start|Start]] page. | ||
urp/physfreq.1636341219.txt.gz · Last modified: 2021-11-08 by nerf_herder
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