Any force caused by actually hitting something. Examples: pushes, punches, pulls, kicks, head butt. When a contact force is exerted by a person, it is sometimes called an applied force.
The force of all masses attracting all other masses.
When on earth, the force of gravity is also called weight an always points downward.
A force that acts perpendicular to a surface. Usually, this is a force that is opposite the force of gravity and holds you up.
A force that affects anything sliding on a surface. Always resists motion.
The force of air pushing back on something as it moves. Air resistance affects things that have a large surface area and move very fast. It is also called drag.
For each question, pick a force.
A free-body diagram shows all of the forces acting on an object, each represented as an arrow.
Drawing good free-body diagrams is the first step to mastering dynamics. Forces cause all changes in motion, and a free-body diagrams shows the forces acting on some object. In this pod, we will begin to draw qualitative free-body diagrams on an object.
For each situation, draw a relevant free-body diagram.
The force of a rope pulling.
When you stretch something our, the elastic force
is the force that pulls back.
Examples: springs, slinkies
The force of an engine pushing something forward.
The force of air pressing on everything around it. It exists constantly in your life, but you never notice it.
A force that pushes upward when air pressure is reduced by an airplane wing. Allows an airplane to fly.
The force of water pressing upward on something. This is the force that allows a boat to float.
For each question or statement, pick a force.
Note that this same video appears in another pod.