Science
Make sense of motion, energy, and the world.
Calculators
Acceleration Calculator
Find average acceleration from a velocity change and elapsed time.
Buoyant Force Calculator
Calculate the upward force associated with displaced fluid.
Density Calculator
Calculate average density from mass and volume.
Dilution Calculator
Calculate stock volume needed for a dilution using C₁V₁ = C₂V₂.
Distance Calculator
Estimate distance from average speed and travel time.
Energy Calculator
Estimate electrical energy in kilowatt-hours from watts and hours.
Force Calculator
Apply Newton’s second law for constant mass in classical mechanics.
Free-Fall Time Calculator
Estimate time to fall from rest through a specified distance.
Frequency from Period Calculator
Find frequency from the duration of one complete cycle.
Hooke’s Law Calculator
Calculate the restoring-force magnitude of an ideal linear spring.
Ideal Gas Pressure Calculator
Estimate pressure using the ideal gas law and absolute temperature.
Hydrostatic Pressure Calculator
Calculate pressure increase below the surface of a static fluid.
Kinetic Energy Calculator
Calculate classical translational kinetic energy from mass and speed.
Molality Calculator
Calculate molality from solute amount and solvent mass.
Moles from Mass Calculator
Calculate amount of substance using entered mass and molar mass.
Molarity Calculator
Calculate molar concentration from solute amount and final solution volume.
Momentum Calculator
Calculate one-dimensional classical momentum.
Pendulum Period Calculator
Estimate the period of a simple pendulum for small swings.
pH from Hydrogen Ion Concentration Calculator
Estimate pH from hydrogen-ion concentration in a dilute ideal solution.
Gravitational Potential Energy Calculator
Calculate gravitational potential-energy change in an approximately uniform field.
Power Calculator
Calculate electrical power for DC or ideal resistive loads.
Pressure Calculator
Calculate average pressure from normal force over an area.
Sensible Heat Calculator
Estimate heat transferred during a temperature change without a phase change.
Speed Calculator
Find average speed from distance and elapsed time.
Solution Mass Percent Calculator
Calculate a solute’s percentage of total solution mass.
Spring Energy Calculator
Calculate elastic potential energy stored in an ideal linear spring.
Wave Speed Calculator
Find wave speed from frequency and wavelength.
Mechanical Work Calculator
Calculate work done by a constant force over a displacement.
Guides & answers
What is the molality of one mole in half a kilogram of solvent?
One mole of dissolved substance in 0.5 kg of solvent has a molality of 2 mol/kg. Use the mass of solvent, not the mass of the entire solution, in the denom
Molarity versus molality
One mole of dissolved substance in 0.5 kg of solvent has a molality of 2 mol/kg. Use the mass of solvent, not the mass of the entire solution, in the denom
Selecting units for solution concentration
One mole of dissolved substance in 0.5 kg of solvent has a molality of 2 mol/kg. Use the mass of solvent, not the mass of the entire solution, in the denom
Energy
Energy is a physical quantity associated with the capacity to do work or transfer heat. The SI unit is the joule.
Power
Power is the rate at which energy is transferred or work is done. Its SI unit is the watt.
Speed
Speed is the rate at which distance is traveled. It is a scalar quantity, so it does not include direction.
How much energy heats two kilograms of water by ten degrees?
Using a constant specific heat of 4,184 J/(kg·K), heating 2 kg of water by 10 K requires 83,680 J, or 83.68 kJ. This estimates heat absorbed by the water,
Temperature change versus heat energy
Using a constant specific heat of 4,184 J/(kg·K), heating 2 kg of water by 10 K requires 83,680 J, or 83.68 kJ. This estimates heat absorbed by the water,
Calculating heat for a temperature change
Using a constant specific heat of 4,184 J/(kg·K), heating 2 kg of water by 10 K requires 83,680 J, or 83.68 kJ. This estimates heat absorbed by the water,
How do you calculate average speed?
Divide total distance by total elapsed time.
How do you calculate electrical power?
For DC circuits, multiply voltage by current: P = V × I.
Speed, Distance, and Time
Speed, distance, and time are linked by distance = average speed × time. Rearrange the equation to solve for another quantity.
What is the difference between watts and kilowatt-hours?
Watts measure power, the rate of energy use. Kilowatt-hours measure total energy used over time.
