General Science: Physics and Measurement Flashcards

Practice flashcards covering units

In physics, how is power defined?

Power is defined as the rate of doing work or of transferring heat or electrical energy, calculated as $Power (P) = \frac{Work (W)}{Time (t)}$.

What is the SI unit of power, and what is its equivalent in joules?

The SI unit of power is the watt ($W$), which is equal to one joule per second ($J/s$).

What are the SI units for electric current, electrical potential, and electric charge?

Electric current is measured in Ampere, electrical potential in Volt, and electric charge in Coulomb.

What is the modern definition of force as given by Isaac Newton?

Force is something that causes a change in the motion of an object, defined as the object's mass multiplied by its acceleration ($Force = mass \times acceleration$).

What is the SI unit of Force?

The SI unit of Force is the Newton ($N$), which is equivalent to $kg \times m/s^2$.

What is the definition of work in physics?

Work is equivalent to the product of force and displacement in the direction of the force ($W = F \times d$). It is a scalar quantity.

What is the SI unit of frequency and how is it defined?

The SI unit of frequency is the Hertz ($Hz$), defined as one cycle per second.

What unit is used to measure the clock speed or processing speed of a computer's central processing unit (CPU)?

The speed is measured in Gigahertz ($GHz$), which indicates the number of cycles the CPU executes per second.

What is the SI unit of electrical resistivity, and what Greek letter represents it?

The SI unit is the ohm-meter ($\Omega m$), and it is represented by the Greek letter $\rho$ (rho).

What are the SI units for Capacitance and Electrical Resistance?

Faraday is the SI unit for Capacitance, and Ohm is the SI unit for Electrical Resistance.

What is the SI unit for magnetic flux density (B-field)?

The SI unit is the tesla ($T$), which is equivalent to one newton per ampere-meter ($1\,N/amp \times m$).

What is the SI unit of radioactivity?

The SI unit of radioactivity is the becquerel ($Bq$), named after Henri Becquerel.

How is a light-year defined?

A light-year is a unit of astronomical distance equivalent to the distance light travels in a vacuum in one Julian year, approximately $9.461 \times 10^{15}$ metres.

What is a parsec?

A parsec ($pc$) is a unit of length equal to the distance at which the average radius of Earth's orbit subtends an angle of $1$ arc second; it is approximately equal to $3.262$ light-years.

How many watts are in one horsepower?

There are $746$ watts in one horsepower ($hp$).

What is an Angstrom (\text{Å})?

An Angstrom is a unit of length used to measure wavelengths of electromagnetic waves, equal to $10^{-10}$ metre or $0.1$ nanometre.

How many grams are in one pikogram?

One pikogram is equal to $10^{-12}$ gram.

What is the SI unit of pressure and its equivalence to Newtons?

The SI unit of pressure is the pascal ($Pa$), which is equivalent to one newton of force applied over an area of one square metre ($1\,N/m^2$).

Why is strain considered dimensionless?

Strain is a ratio of the change in shape or size to the original shape or size; being a ratio of like quantities, it has no unit.

How many litres are in one barrel of oil?

One barrel of oil is equal to $158.9873$ litres (approximately $159$ litres).

What is a 'Dobson unit' used to measure?

The Dobson unit ($DU$) is used to measure the thickness or concentration of the ozone layer in the atmosphere.

What do SONAR and RADAR stand for?

SONAR stands for Sound Navigation and Ranging, and RADAR stands for Radio Detection and Ranging.

What device is used to measure the intensity of solar radiation?

An actiometer (or pyranometer/pyrheliometer) is used to measure the heating power or intensity of solar radiation.

Which medical test is used to detect the electrical activity of the brain?

The Electroencephalogram ($EEG$) is used to monitor brain activity.

What are the formulas for Kinetic Energy (K.E.) and Potential Energy (P.E.)?

$K.E. = \frac{1}{2}mv^2$ and $P.E. = mgh$, where $m$ is mass, $v$ is velocity, $g$ is gravitational acceleration, and $h$ is height.

State the Law of conservation of energy.

Energy can neither be created nor destroyed; it can only be transformed or transferred from one form to another.

What is the escape velocity for Earth?

The escape velocity for Earth is $11.2\,km/second$.

At what temperature does water reach its maximum density?

Water reaches its maximum density at $4^\circ C$ (or $277\,Kelvin$).

What is the approximate speed of light in a vacuum?

The speed of light in a vacuum is approximately $3.0 \times 10^8\,m/s$.

What are the three primary additive colors of light in physics?

The primary additive colors are Red, Green, and Blue.