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## What is a force?????

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**A force is a push…..**PUSH**PULL**… or a pull**FORCES**NOT FORCES • Weight • Magnetism • Friction • Gravity • Thrust • Mass • Inertia • Speed • Acceleration • Velocity**GRAVITY**MAGNETISM WEIGHT**FRICTION**When an object moves in one direction, sliding past another object, friction moves it in the opposite direction!**THRUST**Thrust is a strong push that quickly moves an object**NET FORCE is the combining of ALL forces on an object**• Each person is putting a force on the rope! • Combined, they have a net force!**Forces moving in opposite directions are subtracted**20N 10N NET FORCE ON THE CAR = 10 N**30 N**NET FORCE ON THE TOY = 15N 15 N**Forces moving in the same direction are added**12 N 12 N NET FORCE ON THE CAR = 24 N**Newton’s 1st Law of Motion**Objects at rest remain at rest, objects in motion remain in motion, unless acted on by an unbalanced force.**BALANCED FORCES**• All forces acting on an object are equal and opposite in direction. • Net force equals zero • Causes no change in motion of the object**BALANCED FORCES**20 N 20 N NET FORCE = 0N NO MOVEMENT!!!!!**20N**20N NET FORCE ON THE CAR= 0N**UNBALANCED FORCES**• All forces acting on an object are NOT equal • The net force will NOT be 0 N • There WILL be a change in motion**The force of the boys pushing on the car, is greater than**the force of friction. • The forces are unbalanced. 24 N FRICTION 4 N What is the NET FORCE? Which direction will the car move?**10 N**50 N**Which way is this car going to move?**100 N 10 N**The car is in motion, until acted on by the wall.**• The wall has more force than the car, so it will be stopped**This plane has a constant airspeed.**• When a force (THRUST) is acted on it, the airspeed will increase, and the plane will accelerate. • If a different force (DRAG) is acted on it, the airspeed will decrease, and the plane will slow down.**The soccer ball remains at rest, until someone exerts thrust**on it by kicking it. The pitcher throws a baseball in a certain pathway. The batter exerts a thrust on the ball with the bat, and the ball changes direction.**Newton’s 2nd Law of Motion**Force (F) = mass (m) x acceleration (a)**Newton’s 3rd Law of Motion**For every action, there is an equal and opposite reaction.