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Forces of Motion. Forces to reckon with…. Force. A force is a push or pull exerted on an object in order to change the motion of an object Force has two things Size Direction *Similar to velocity and acceleration. Units. Force is measured in something called Newtons
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Forces of Motion Forces to reckon with…
Force • A force is a push or pull exerted on an object in order to change the motion of an object • Force has two things • Size • Direction *Similar to velocity and acceleration
Units • Force is measured in something called Newtons • Named after Isaac Newton • Are in units of kg (m/s^2) • Kg = Mass • m/s^2 = Acceleration • Force = Mass x Acceleration
Net Force • Net Force is simply the combination of all the forces acting on an object • Ex) Two guys try to move a piano. One guy is pulling with a force of 30 Newtons and another guy is pushing with a force of 24 Newtons. What is the net force on the piano? = 24 N 30 N
Net Force • A guy is trying to push a desk across a carpet floor. He is pushing with a force of 35 Newtons and the carpet’s friction is slowing it down with a force 9 Newtons. What is the net force? = 9 N 35 N
Balanced Forces • Balanced Forces are when the forces on an object produce a net force of 0 Newtons. • In other words the balanced forces will not cause a change in the motion of a moving object or make a non-moving object start moving
Unbalanced Forces • When the net force on an object is not 0 Newtons, the forces on the object are said to be unbalanced. • Unbalanced forces cause a change in the motion of an object and are necessary to get an object to start moving
Balanced and Unbalanced Forces • If two teams of people are playing tug of war and each team is pulling the rope with a force of 12 Newtons. Is the rope balanced? What is the net force?
Balanced and Unbalanced Forces • What if there is an elevator of people with a force of 195 Newtons pulling down and a tension force of 317 Newtons pulling up. Is the Elevator balanced? What is the net force?
Types of Forces • There are several types of forces of motion • Some increase motion • Some oppose motion
Friction • Friction is a force that opposes motion between two surfaces that are in contact • Examples include • Rubbing hands together • Pushing a heavy object over a rough surface • Pouring sand on ice
Gravity • A force of attraction between objects due to their masses • We consider gravity a downward force on Earth, since everything is pulled toward its center
Buoyancy • Buoyancy is the force that pushes objects that are less dense than water upward • Example • Ships • Person in water • Block of wood • Inner tube
Tension • Tension is the pulling force applied to a rope or a spring that attempts to stretch it out
Tension • If you walk your pet, you would use a leash or a rope. There would be a tension force in the rope if it was trying to walk faster than you • Ex) Your pet pig pulls you down the street with a force of 12 Newtons
Magnetism • A magnetic force is found between two magnets • The magnetic force can be repulsive or attractive • Attractive force = a positive end and a negative end • Repulsive force = two positive ends or two negative ends
Magnetic Force • Each magnet has a positive and negative end. • Opposites attract, Same repels
Normal Force • Normal Force is the force of an object pushing back against an object pushing on it. • Ex) Person on a chair Book on a desk Box on the ground