Download - Balanced and Unbalanced Forces
Forces
Force• Force is simply a push or a pull.– The Newton is the unit used to express force.
• When you pull a stuck door, you are applying more force to the door.
Forces Act on Objects
• A force is always exerted by an object and always acts on another object.
Net Force
• Net force is the result from combining all the force exerted on an object.
Net Force
• A net force acting on a stationary object will move the object.
Force
• Forces come in pairs• Forces have a magnitude and a direction
5N, north (up) Magnitude: 5NDirection: north (up)
Balanced and Unbalanced Forces
• Forces occur in pairs and they can be either balanced or unbalanced
Balanced Forces
• A stationary object will not move while the forces acting on it are balanced.
Balanced Forces
• Balanced forces do not cause change in motion
• They are equal in size and opposite in direction
Unbalanced Forces
• When the net force of an object is not zero, the forces on the object are unbalanced.
• An unbalanced force always causes a change in motion
Unbalanced Forces
3 N, right – 6 N, left = 3N, left
Unbalanced Forces
4 N, left – 10 N, right = 6N, right
Newton’s Second Law of Motion• Force = mass X acceleration• F = ma• Force and acceleration are directly
proportional. The greater the force, the greater the acceleration.
• Mass and acceleration are inversely related. The greater the mass of an object the less the acceleration if the same force is applied.
What is friction?
• Friction is a force which opposes motion.• Friction is an important force in our lives. We
rely on friction in many ways. An athlete usually wears shoes which provide him or her with a greater friction between the shoe and the surface. We rely on friction as an important aspect of our motion. In what other ways does friction play a role in our everyday lives?
Air Resistance – another type of friction??
• Air resistance is a force which opposes a moving object. This can be easily seen with falling objects. When a piece of paper and a crumple piece of the same type of paper are dropped, they fall at the same rate.
• A penny and a feather dropped in air will not fall at the same rate, but a penny and feather dropped in a vacuum (no air) will.
• Gravity is a force of attraction between two objects.• Law of Gravitation – any two masses exert an
attractive force on each other. The amount of attraction depends upon two things: the mass of the objects and the distance between the objects.
What is Gravity?