Velocity is a vector quantity because it has both magnitude and direction.

The SI unit of electric current is the ampere, which is defined as the flow of one coulomb of charge per second.

Temperature is a scalar quantity because it has only magnitude and no direction.

The law of conservation of energy states that energy can be transferred from one form to another, but it cannot be created or destroyed.

The four fundamental forces of nature are gravitational force, electromagnetic force, strong nuclear force, and weak nuclear force.

The SI unit of mass is the kilogram, which is defined as the mass of a specific platinum-iridium cylinder kept at the International Bureau of Weights and Measures in France.

The SI unit of time is the second, but minutes, hours, and days are also commonly used units of time.

The SI unit of length is the meter, which is defined as the distance traveled by light in a vacuum in 1/299,792,458 of a second.

The SI unit of energy is the joule, but calories, British thermal units, and electronvolts are also commonly used units of energy.

The SI unit of electric charge is the coulomb, which is defined as the amount of charge carried by one mole of electrons.

The SI unit of power is the watt, but horsepower, British thermal units per hour, and calories per second are also commonly used units of power.

The SI unit of temperature is the kelvin, which is defined as 1/273.16 of the thermodynamic temperature of the triple point of water.

The SI unit of pressure is the pascal, but atmospheres, bars, and pounds per square inch are also commonly used units of pressure.

The SI unit of volume is the cubic meter, which is defined as the volume of a cube with sides of one meter.

The SI unit of frequency is the hertz, which is defined as one cycle per second. Cycles per second, revolutions per minute, and beats per minute are also commonly used units of frequency.