Types of Forces
This type of force is the force applied to an object by another object or person pushing or pulling it.
What is applied force?
This is force symbol for gravitational force.
What is Fg?
All the forces on an object are this if the object is motionless.
What is balanced?
True or false? When drawing free body diagrams, the object is drawn as a realistic sketch.
False. It is drawn as a simple, empty box
A yoyo is hanging motionless by its string. Draw a free body diagram for the yoyo.
Motionless = balanced
Fg & FT
This type of force is a special kind of frictional force that acts on objects as they travel through the air.
What is air resistance force?
This is the force symbol for applied force.
What is FA?
All the forces on an object are this if the object is moving with constant velocity.
What is balanced?
What is an arrow?
You apply a force to your bike by pedaling to the right. You are moving with constant velocity. Consider frictional forces. Neglect air resistance. Draw a free body diagram for the bike.
Constant velocity = Balanced
Fg, FN, FA, Ff
This type of force moves through a string, rope, cable, or wire when pulled tight from opposite ends.
What is tension force?
This is the force symbol for frictional force.
What is Ff?
The forces on an object are this if the object is speeding up.
What is unbalanced?
True or false? Gravitational force is drawn as an arrow pointing straight up in a free body diagram.
False. It is drawn pointing straight down.
You are skateboarding and your friend is pulling you with a rope behind their bike. You are speeding up the right. Consider frictional forces. Neglect air resistance. Draw a FBD for you on the skateboard.
Speeding up = Unbalanced
Fg, FN, FT, Ff
This type of force is exerted by a surface as an object moves across it. It acts against the motion of the object.
What is frictional force?
This is the force symbol for normal force.
What is FN?
These type of forces result in no change to an object's motion.
What are balanced forces?
When drawing a free body diagram for an object moving with constant velocity, all arrows should be this size.
What is the same size?
While driving, you approach a yellow stoplight. You let your foot off the gas pedal and coast (no gas, no brakes). Your car slows down. Consider frictional forces. Neglect air resistance. Draw a FBD for the car.
Slow down = Unbalanced
"Coast" = No applied force to the right
Fg, FN, Ff
This type of force is exerted by a surface that supports the weight of an object.
What is normal force?
This is the force symbol for air resistance force.
What is Fair?
These type of forces do not cancel each other and result in a change to the object's motion.
What are unbalanced forces?
True or false? It is possible for an object to be accelerating to the right while a force is acting on it to the left.
True! You can push a book across a desk with rightward acceleration while frictional force acts against its motion to the left.
Slows down = Unbalanced
Fg & Fair