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🔬 ScienceFree
AHU mixed air temperature
In an air-handling unit, 0.4 kg/s of outdoor air at 35 °C mixed with 1.6 kg/s of return air at 24 °C reaches the coil at 26.2 °C.
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AM modulation index calculator
A 2 V message on a 5 V carrier gives a modulation index of 0.4, or 40 %. Enter both peak amplitudes in the same unit to see whether an AM signal is…
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Mohr's circle calculator
Normal stresses of 80 and 20 with a shear of 40 give principal stresses of 100 and 0 and a maximum shear of 50, in whatever unit you use.
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MOSFET threshold voltage
A flat-band voltage of -0.9 V, a body coefficient of 0.5 and a surface potential of 0.7 V, with the body tied to the source, give a threshold just over two…
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NE555 astable calculator
Timing resistors of 4.7 kΩ and 10 kΩ with a 100 nF capacitor make an NE555 astable run at a duty cycle of 59.5 %.
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Newton's third law calculator
Push on a wall with 12 N to the right and the wall pushes back with 12 N to the left, written as -12.
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NPSH calculator
Water at 200000 Pa absolute suction pressure, with a vapor pressure of 2000 Pa and a velocity head of 0.5 m, has just over twenty metres of NPSH available.
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Ohm's law current calculator
A 12 V battery across a 4 Ω heater drives 3 A. Enter the voltage across a load and its resistance to get the direct current in amperes, with the sign kept for…
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Ohm's law power calculator
A 12 V supply pushing 2 A delivers 24 W. Enter any two of voltage, current and resistance to get the power in watts and see which identity was used: V times I…
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Open channel flow calculator
A channel with 3 m² of flow area, a hydraulic radius of 0.6 m, a slope of 0.001 and a roughness of 0.015 carries about four and a half cubic metres per second.
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Optical density calculator
If 100 units of light reach a sample and 10 get through, transmittance is 0.1 and optical density is exactly 1.
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Parallel capacitor calculator
Capacitors of 1, 2.2 and 4.7 µF in parallel, entered as 0.000001, 0.0000022 and 0.0000047 farads, add up to 0.0000079 farads.
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Parallel inductors calculator
Two 10 H coils in parallel act as a single 5 H inductor, and 4, 6 and 12 H together give 2 H. Enter the inductance of each branch in henries and get the…
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Particle velocity calculator
A particle with 9 J of kinetic energy and a mass of 2 kg moves at 3 m/s. Enter the energy in joules and the mass in kilograms to get the speed of anything from…
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Performance coefficient calculator
A refrigerator that removes 400 J of heat from its cold side using 100 J of work has a COP of 4. Enter the heat absorbed and the work supplied and get the…
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Photoelectric effect calculator
A 1000 THz photon carries 6.62607015 × 10⁻¹⁹ J, so a metal with a work function of 3 × 10⁻¹⁹ J releases electrons that keep the surplus as kinetic energy.
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Photon energy calculator
A photon with a 500 nm wavelength carries nearly 4 × 10⁻¹⁹ joules. Enter a wavelength in metres or a frequency in hertz and get the energy from Planck's…
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Piston force calculator
A pressure of 1 MPa on a 0.1 m bore pushes the piston with almost 8 kN. Enter the cylinder pressure in pascals and the bore in metres to get the full-bore force…
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Piston speed calculator
An 86 mm stroke at 6000 rpm gives a mean piston speed of 17.2 m/s. Enter the stroke in millimetres, metres or inches and the crank speed to get the average in…
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Pneumatic cylinder force calculator
At 6 bar of shop air, a cylinder with a 0.05 m bore pushes out with about 1178.1 N. Enter supply pressure in pascals and bore in metres to get the extension…
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Polar moment of inertia calculator
A solid shaft 0.1 m across has a polar moment of about 9.817 × 10⁻⁶ m⁴. Enter the outer diameter in metres to get J = πd⁴/32, the figure that goes into…
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Pounds per minute converter
Sixty pounds per minute is exactly 0.45359237 kg/s, because the minute cancels and only the exact pound is left.
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Pounds per square inch converter
One psi is about 6894.757293168 pascals, or 0.068947572932 bar. Type a tyre, compressor or hydraulic reading in pounds per square inch and get pascals, bar and…
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Prandtl-Meyer expansion calculator
At Mach 2 in air, with γ of 1.4, the flow has turned about 26.38° from sonic conditions and the Mach angle is 30°.
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Principal stress calculator
With 80 on the x-face, 20 on the y-face and a shear of 40, the principal stresses are 100 and 0. Enter the two normal stresses and the in-plane shear in one…
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Projectile motion calculator
A ball launched at 20 m/s and 45° from 10 m up peaks about 20 m above the ground. Enter speed, angle and launch height to get the range, the maximum height and…
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Pulley calculator
A 400 N load shared by 4 supporting rope segments needs only 100 N of pull. Enter the load and the number of segments to get the mechanical advantage, the rope…
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Quantum number calculator
The numbers 2, 1, 0 and +1/2 describe a valid electron in a 2p orbital, which holds 2 electrons. Enter n, l, ml and ms to check them against the selection rules…
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Projectile motion range calculator
On level ground a launch at 45° goes farthest, because the range then reduces to speed squared over g.
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RC circuit calculator
With 5 V through 1 kΩ into 1 µF, the capacitor reaches about 3.16 V after 1 ms, exactly one time constant.
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Reaction time calculator
At 20 m/s, a driver who needs 1.5 s to react covers 30 m before touching the brake. Enter speed and reaction time to get the thinking distance, the stretch of…
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Refrigerant capillary tube calculator
A 0.8 mm capillary carrying 1.5 kg/h of R134a needs a length of just under 3 m. Enter inner diameter, refrigerant and design mass flow to get a first-cut length…
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Relativistic kinetic energy calculator
At a tenth of the speed of light, the true kinetic energy is already a few percent above the classical ½mv².
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Resistor wattage calculator
A 100 Ω resistor carrying 0.05 A turns 0.25 W into heat, so it needs at least a 0.25 W rating. Enter resistance in ohms and current in amperes to get the…
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RLC circuit calculator
A series circuit of 10 Ω, 1 mH and 1 µF resonates at just over five thousand hertz, with a quality factor a little above 3.
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RLC impedance calculator
At 50 Hz, a series circuit of 100 Ω, 0.2 H and 10 µF is dominated by the capacitor, so its phase is negative and voltage lags current.
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RMS speed calculator
Quadruple the absolute temperature of a gas and the root-mean-square speed of its molecules doubles.
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Rotational stiffness calculator
A steel shaft with a shear modulus of 80 GPa, a polar moment of 1 × 10⁻⁸ m⁴ and a length of 0.5 m takes 1600 N·m to twist one radian.
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Rydberg equation calculator
An electron falling from level 3 to level 2 in hydrogen emits the Balmer H-alpha line at 656.112276418 nm in vacuum.
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Section modulus calculator
A section with I of 0.0001 m⁴ and its farthest fibre 0.05 m from the neutral axis has a section modulus of 0.002 m³.
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Shaft size calculator
A torque of 1000 N·m with an allowable shear of 40 000 000 Pa needs a solid shaft just over fifty millimetres across.
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Shear modulus calculator
A shear stress of 80 MPa that produces a shear strain of 0.001 means a shear modulus of 80 GPa, typical of structural steel.
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Shear wave velocity calculator
A solid with a shear modulus of 81 000 000 000 Pa and a density of 9000 kg/m³ carries shear waves at 3000 m/s.
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Simple harmonic motion calculator
With an amplitude of 4, an angular frequency of 2 rad/s and zero phase, the oscillator sits at +4 at time zero, at rest, with an acceleration of −16.
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Simple pendulum calculator
A 1 m pendulum under standard gravity, 9.80665 m/s², takes about 2 s for one full cycle. Enter the length from pivot to centre of mass and the local gravity to…
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Slenderness ratio calculator
A column with an effective length of 4000 mm and a least radius of gyration of 50 mm has a slenderness ratio of 80.
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Sound wavelength calculator
Concert A at 440 Hz in room air, where sound travels at 343 m/s, has a wavelength of about 0.78 m.
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Space travel time dilation
At 60% of light speed the Lorentz factor is 1.25, so clocks aboard run at 0.8 times the Earth rate.
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Specific gravity calculator
Aluminum at 2.7 g/cm³ against water at 1 g/cm³ has a specific gravity of 2.7, so it is denser than water.
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Speed of sound in solids
A steel bar with a Young's modulus of 2 × 10¹¹ Pa and a density of 8000 kg/m³ carries sound at 5000 m/s.
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Speeds and feeds calculator
A 10 mm end mill cutting at 100 m/min must turn at just over three thousand rpm. Add the number of teeth and the chip load per tooth and you also get the table…
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Spring calculator
A spring with a constant of 80 N/m stretched by 0.05 m pulls back with a force of −4 N, the minus sign pointing toward rest.
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Stefan-Boltzmann law
A black body with 1 m² of surface at 300 K radiates 459.300327939 W. Enter the area and the temperature in kelvin to get the total radiated power, with…
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Stokes' law calculator
A sphere of radius 0.0001 m and density 2500 kg/m³ settles at 0.0327 m/s through a liquid of 1000 kg/m³ and 0.001 Pa·s.
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Stopping distance calculator
At 20 m/s with a 1.5 s reaction time and 8 m/s² of braking, a car covers 30 m before braking starts and 25 m while braking, 55 m in all.
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Sunset time calculator
At the equator, with the Sun's declination at 23.44°, the Sun sets at 6 p.m. solar time, a 90° hour angle after noon.
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SUVAT calculator
Starting at 10 m/s with an acceleration of 2 m/s², a body reaches 20 m/s after 5 s. Enter the initial velocity, the acceleration and the time, then choose…
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Telescope field of view
A 50° eyepiece at 40× magnification shows 1.25° of real sky, enough for the full Moon with room to spare.
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Thermal energy calculator
Warming 2 kg of water by 10 °C, with a specific heat of 4184 J/(kg·K), takes 83680 J. Enter the mass, the specific heat and the temperature change to get the…
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Thermal expansion calculator
A 10 m steel member heated by 50 °C, with a coefficient of 0.000012 per kelvin, grows by 0.006 m to 10.006 m.
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