Tell me a physics joke
Q: What happens when electrons lose their energy?
A: They get Bohr'ed.
Why did the chicken cross the Möbius strip?
To get to the same side.
(A fine question since, as every mathematician knows, a Möbius strip is a nonorientable surface that has only a single side.)
Doppler shift |
the frequency at the source | 300 Hz (hertz)
speed of the source away from the observer | 75 mph (miles per hour)
sound speed | 340.27 m/s (meters per second)
frequency observed | 273.1 Hz (hertz)
= 0.2731 kHz (kilohertz)
f_o/f_s = c/(c + v_s) |
f_o | frequency observed
f_s | frequency at the source
v_s | speed of the source away from the observer
c | sound speed
(the ratio between emitted and observed sound frequencies due to relative motion)
source: 300 Hz (hertz) | observed: 273.1 Hz (hertz)
accelerograph | A device that consists of a strong motion seismograph or an earthquake accelerometer.
accelerometer (generic) | A device that measures proper acceleration.
actigraph | A device is worn by a patient to measure gross motor activity.
capacitive accelerometer | A device that measures proper acceleration by detecting changes in capacitance due to the shifting of capacitive plates.
gravity gradiometer | A device used to measure the gradient in gravitational acceleration.
linear accelerometer | A device that measures proper acceleration along a single axis.
MEMS accelerometer | A device that measures acceleration using micrometer-scale sensors.
metrosphere | A theoretical device that incorporates the functions of a clock, rod, nonrotating platform, and accelerometer, and whose operation depends on the properties of light rays and free particles.
omnidirectional accelerometer | A device that measures proper acceleration in any direction.
piezoelectric sensor | A device that uses the piezoelectric effect to measure changes in pressure, acceleration, strain, or force by converting them to an electrical charge.
PIGA accelerometer | A type of accelerometer that can measure acceleration and simultaneously integrates this acceleration against time to produce a speed measure as well.
triaxial accelerometer | A device that measures proper acceleration in three orthogonal directions.
MEMS accelerometer | surface micromachined capacitive accelerometer
piezoelectric sensor | integrated circuit piezoelectric sensor
PIGA accelerometer | pendulous integrating gyroscopic accelerometer | PIGA
maximum spring force
F_max = (E d^4 (L - n d))/(16 (1 + ν) (D - d)^3 n) |
F_max | maximum spring force
D | spring outer diameter
d | spring wire diameter
L | free length of spring
E | Young modulus
ν | Poisson ratio
n | number of active windings
(force of fully compressed spring)
spring outer diameter | 1 cm (centimeter)
spring wire diameter | 2 mm (millimeters)
free length of spring | 50 cm (centimeters)
Young modulus | 211 GPa (gigapascals)
Poisson ratio | 0.3
number of active windings | 5
maximum spring force | 31.07 kN (kilonewtons)
= 6984 lbf (pounds-force)
= 31067 N (newtons)
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