Unit 5 Reassessment Review - FORCES Directions: To view this presentation correctly click “Slideshow” then “From Beginning”. There are many animations and helpful examples so read carefully! Take notes when you see the pencil. Use page titles as subheadings to keep your notes organized.

Balanced & Unbalanced Forces

Force 1000 kg What is force? Push or Pull It’s what causes “things” to accelerate 1000 kg

Net Force The combination of all forces acting on an object.

Adding Forces 5 N 5 N = 10 N Two forces in the same direction are added together to produce a net force in that direction.

Subtracting Forces 10 N = 5 N 5 N When forces are in opposite directions you subtract to produce a net force that will move in the direction of the larger force.

Balanced Forces If all forces are balanced there is no acceleration in any direction. The Net Force is 0N.

Balanced Forces (Balanced Forces = No Acceleration) Object 5 N 5 N Notice that all the forces are equally pointed in the opposite direction. Hence they balance each other – or cancel each other. Equal Pushing Forces may cancel each other and produce a Net Force of 0!

Balanced Forces Example (Balanced Forces = No Acceleration) Ground pushes up Gravity pulls down Gravity pulls down on you… The ground pushes back up… THIS KEEPS YOU WHERE YOU ARE! If these football players push on each other equally as hard, will either one move?

Balanced Forces Example (Balanced Forces = No Acceleration) Equal Pushing Equal Pulling 5 N 5 N Forces may cancel each other and produce No Acceleration!

Balanced Forces Balanced Push No Change in Motion i.e. Pushing a Car Pull i.e. Tug-o-war 10N 10N 10N 10N

Unbalanced Forces If one force is greater than the opposing force we get acceleration in a direction. The net force will NOT be equal to 0N.

Unbalanced Forces Cause Acceleration Adding Forces Subtracting Forces

Unbalanced Forces Causes Acceleration Adding Forces Object 5 N 5 N Notice that all the forces are pointed in the same direction. Hence they add together.

Unbalanced Forces Causes Acceleration Subtracting Forces Object 20 N 5 N Net Force of 15N to the Right Notice that the forces are unequal and pointed in the opposite direction. Hence they are unbalanced and in opposition to each other – or one partially cancels the other.

Un-Balanced Forces Additive Un-Balanced Same Direction so you ADD 10 + 10 Moves 20 N to the Right. Subtractive Opposite Direction So you SUBTRACT 20 - 10 Moves 10 N to the right 10N 10N 20N 10N