1.1 Forces
Dynamics is the study of the forces that cause objects and systems to move. Our innate
understanding of force is that it is a push or a pull. But a much better description of force is that
it is an interaction between an object and its environment. You push a crate or pull a piano, push
a cart in a supermarket. When you push or pull on an object, you exert a force on that object.
You can be the environment interacting with the object. Figure 1.1 shows various ways of
interactions between doer of the force (person) and the receiver of the force (box, crate, and
wheelbarrow).
Figure 1.1 A force is a push or pull the represents an interaction between the object and its
environment. (credit: https://www.uen.org/lessonplan/view/32852)
Force is a vector quantity, thus, it has magnitude and direction. You can exert push or pull in
various directions.
When there is direct contact between the object of interest and its environment, then the force
involved is identified as contact force. How many contact forces do you know? Here is a short
list of contact forces:
Normal force (𝑛⃗) is exerted on an object by any surface it is contact with. It is an everyday
force that is felt when a surface pushes against an object that is placed on that surface. For
example, when a box is placed on a table, the normal force keeps the book from falling
through the table. This force always act perpendicular to the surface of contact
Figure 1.2 Normal forces are always directed perpendicular to the surface
over which the object is in contact with.
Dynamics is the study of the forces that cause objects and systems to move. Our innate
understanding of force is that it is a push or a pull. But a much better description of force is that
it is an interaction between an object and its environment. You push a crate or pull a piano, push
a cart in a supermarket. When you push or pull on an object, you exert a force on that object.
You can be the environment interacting with the object. Figure 1.1 shows various ways of
interactions between doer of the force (person) and the receiver of the force (box, crate, and
wheelbarrow).
Figure 1.1 A force is a push or pull the represents an interaction between the object and its
environment. (credit: https://www.uen.org/lessonplan/view/32852)
Force is a vector quantity, thus, it has magnitude and direction. You can exert push or pull in
various directions.
When there is direct contact between the object of interest and its environment, then the force
involved is identified as contact force. How many contact forces do you know? Here is a short
list of contact forces:
Normal force (𝑛⃗) is exerted on an object by any surface it is contact with. It is an everyday
force that is felt when a surface pushes against an object that is placed on that surface. For
example, when a box is placed on a table, the normal force keeps the book from falling
through the table. This force always act perpendicular to the surface of contact
Figure 1.2 Normal forces are always directed perpendicular to the surface
over which the object is in contact with.
