TABLE OF CONTENTS Engineering mechanics can be divided into statics and dynamics. Basically, statics is the study of forces and their effects in equilibrium, whereas dynamics is the study of objects in motion.
Mass is the quantity of matter in a body. It is the sum total of the masses of all the subatomic particles in that body.
Matter occupies space and can be solid, liquid or gaseous.
Unless matter is added to or removed from a body, the mass of that body never varies. It is constant under all conditions. There are as many atoms in a kilogram of, say, metal on the moon as there are in the same kilogram of metal on planet Earth. However, that kilogram of metal will weigh less on the moon than on planet Earth (see Section 2.2.4).
The basic unit of mass is the kilogram (kg). The most commonly used multiple of this basic unit is the tonne (1000 kg) and the most commonly used sub-multiple is the gram (0.001 kg).
To understand how mass and weight are related it is necessary to consider the concept of force. A force or a system of forces cannot be seen; only the effect of a force or a system of forces can be seen. That is:
A force can change or try to change the shape of an object.
A force can move or try to...
