# what is force?

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What is Force?. What is Force?. What is force? A push or pull on an object that changes the motion of the object. Force is measured in Newtons SI unit symbol is N 1 N = the gravity on Earth of 100g of mass - PowerPoint PPT Presentation

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What is Force?

What is Force?What is Force?What is force?A push or pull on an object that changes the motion of the object.Force is measured in NewtonsSI unit symbol is N1 N = the gravity on Earth of 100g of mass

There has to be something receiving the force as well as something applying the force.What is Force?You can not always see the force being exertedGravityStatic electricityOthersNet ForceThe combination of all the forces acting on an objectExample

4 N4 NNet Force = 8NNet ForceThe combination of all the forces acting on an objectExample

4 N1 NNet Force = 3NBalanced ForcesThe combination of all forces acting on an object.Example

4 N4 N4 N4 N4 N4 N4 N4 NNet Force = 0 NBalanced ForcesThe combination of all forces acting on an object.Example

5 N8 N10 N5 N10 N8 N4 N4 NNet Force = 0 NUnbalanced ForcesThe combination of all forces acting on an object are not equal.Example

4 N4 N4 N5 N4 N4 N4 N4 NNet Force = 1 NUnbalanced ForcesThe combination of all forces acting on an object are not equal.Example

5 N6 N10 N5 N10 N6 N4 N8 NNet Force = 4 NUnbalanced ForcesThe combination of all forces acting on an object are not equal.Example

5 N6 N10 N1 N10 N6 N4 N8 NUnbalanced ForcesUnbalanced forces can cause a change in motionWhat is Friction?Friction is the force that opposes motionFriction occurs when two objects slide over each otherThe amount of friction depends on several factorsThe roughness of the surfacesThe force pushing the surfaces together

What is Friction?The amount of friction depends on several factorsThe roughness of the surfacesThe force pushing the surfaces togetherIncludes the downward force and the horizontal force.

Types of FrictionThere are two types of frictionKineticKinetic friction is the force that tries to slow a moving object downStaticStatic friction is the force that tries to prevent an object at rest, from movingOvercoming the affects of FrictionThere are other types of frictionSlidingSliding friction happens when two objects slide over each otherExamplePushing a crate across the floorOvercoming the affects of FrictionRollingRolling friction happens when an object slides on rollers or wheelsExampleSkates, a wagon, markers under a bookOvercoming the affects of FrictionFluid frictionFluid friction happens when an object slides over a surface that has a layer of fluid on itExampleWater on the floorOil in an engine.

Gravity

Isaac Newton1665 under an apple tree

GravityIsaac NewtonTwo questions?Why do things fall to the Earth?Why do the planets stay in motion?GravityGravityThe force of attraction between two bodiesAll matter has mass, therefore all matter has gravityGravityThe Law of Universal GravitationGravitational force increases as mass increasesGravitational force decreases as distance increasesGravityGravity and MotionGalileo dropped two cannon balls from the tower at Pisa .Each cannon ball had a different massThey both hit the ground at the same timeGravity accelerates all objects at the same rate9.8 m/s/s (4.9m/s first second and 9.8 every second after).

V = 0m/sV = 9.8m/sV = 19.6m/sV = 29.4m/s4.9m14.7m24.5mGravityGravity accelerates all objects at the same rate9.8 m/s/s (4.9m/s first second and 9.8 every second after)Air ResistanceSimilar to friction in that it opposes the motion of a falling object in air

GravityTerminal VelocityWhen the force of air resistance is equal to the force of gravity and a falling object no longer accelerates

GravityTerminal Velocity . . When the force of air resistance is equal to the force of gravity and a falling object no longer accelerates Free fall Only the force of gravity is pulling on an object

GravityFree fall .Only the force of gravity is pulling on an objectOrbits . . .A combination of forward motion and the downward pull of gravityProjectile MotionThe curved path that an object takes when thrown or launched

Projectile MotionThe curved path that an object takes when thrown or launched

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