The SI unit of work is the joule (J), which is defined as the amount of work done when a force of one newton is applied over a distance of one meter in the direction of the force.

The formula for calculating the work done by a constant force is $W = F \cdot d$, where $W$ is the work done, $F$ is the force applied, and $d$ is the displacement of the object in the direction of the force.

Work and energy are equivalent, meaning that work done on an object results in a transfer of energy to that object.

There are many different forms of energy, including kinetic energy, potential energy, thermal energy, mechanical energy, electrical energy, chemical energy, nuclear energy, radiant energy, and sound energy.

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

The formula for calculating kinetic energy is $K = \frac{1}{2}mv^2$, where $K$ is the kinetic energy, $m$ is the mass of the object, and $v$ is the velocity of the object.

The formula for calculating potential energy due to gravity is $U = mgh$, where $U$ is the potential energy, $m$ is the mass of the object, $g$ is the acceleration due to gravity, and $h$ is the height of the object above a reference point.

Power is the rate at which work is done, meaning that it measures how quickly work is being transferred or transformed.

The SI unit of power is the watt (W), which is defined as the rate at which work is done when one joule of energy is transferred or transformed in one second.

The formula for calculating power is $P = W/t$, where $P$ is the power, $W$ is the work done, and $t$ is the time taken to do the work.

The efficiency of a machine is the ratio of output work to input work, which measures how much of the input work is converted into useful output work.

The formula for calculating the efficiency of a machine is $e = \frac{W_{out}}{W_{in}}$, where $e$ is the efficiency, $W_{out}$ is the output work, and $W_{in}$ is the input work.

The principle of conservation of energy in the context of machines states that energy is transferred from one form to another, but it is not created or destroyed.

Work is a scalar quantity, meaning that it has only magnitude, while energy is a scalar quantity, meaning that it has both magnitude and direction.

The SI unit of energy is the joule (J), which is defined as the amount of energy transferred or transformed when a force of one newton is applied over a distance of one meter in the direction of the force.