How to Draw a Force Diagram to Find the Net Force Acting on an

Object

• First, identify the object (or the system of objects) which you wish to study.

• In this example, our system will be Ms. Clanton standing still in the physical science classroom

• Next, draw a rectangle or a circle to represent the object (or system of objects) which you are studying.

• Draw a dashed circle around the object you are studying; the dashed circle represents the system you are studying. Only the object (or system) you are studying is in the dashed circle; everything else is outside.

• Next, draw a rectangle or a circle to represent the object (or system of objects) which you are studying.

• Draw a dashed circle around the object you are studying; the dashed circle represents the system you are studying. Only the object (or system) you are studying is in the dashed circle; everything else is outside.

• Then, draw everything which touches the object (or system of objects) which you are studying.

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

Contact Force:

Support Force

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

Contact Force:

Support Force

Support Force

sF

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

Support Force

sF

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

Support Force

sF

Gravity always pulls down on an object if

the object is at or near the surface of

the earth.

• Next, identify any forces which are acting on the object you are studying.– At least one contact

force acts at each point where the object you are studying is touched.

– Identify any forces which act at a distance (gravity, for instance).

Support Force

sF

Gravity always pulls down on an object if

the object is at or near the surface of

the earth.

Force of Gravity

gF

• Finally, you can find the net force acting on the object you are studying by adding up all of the force vectors in the diagram.

• For this example, the force vectors are equal in size but opposite in direction. So, they cancel out.

• The net force acting on the object we are studying is zero.

Support Force

sF

Force of Gravity

gF

• Finally, you can find the net force acting on the object you are studying by adding up all of the force vectors in the diagram.

• For this example, the force vectors are equal in size but opposite in direction. So, they cancel out.

• The net force acting on the object we are studying is zero.

Support Force

sF

Force of Gravity

gF

• Finally, you can find the net force acting on the object you are studying by adding up all of the force vectors in the diagram.

• For this example, the force vectors are equal in size but opposite in direction. So, they cancel out.

• The net force acting on the object we are studying is zero.

Support Force

sF

Force of Gravity

gFNet Force = 0