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Forces and Motion… Everyday pushes and pulls (that we never think about)

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Forces and Motion… Everyday pushes and pulls (that we never think about)

Everyday Forces Forces GravitationMagnetismFriction Which two forces have we studied this year?

Gravity: the pull between all objects (the greater the mass, the harder the pull!!!) Discovered by Sir Isaac Newton when an apple fell upon his head…

Friction: causes motion to slow down or stop… causes drag! Friction keeps us from sliding off the skateboard. The rough surface of the mountain causes friction and gives us a grip on the side of the mountain when we rock climb. The tread on our shoes causes friction, and keeps us from ending up like this guy on icy roads.

Balanced forces are equal in size and opposite in direction. When forces are balanced, no change in motion occurs.

Unbalanced forces are NOT equal in size and opposite in direction. When forces are unbalanced, a change in motion occurs.

How can I tell when motion is occurring??? I need to know an object’s starting position to be able to tell it has moved over a distance! Distance

Speed: How long it takes to travel a given distance Formula: Distance/Time = Speed Formula: Distance/Time = Speed Ex: 55 miles/1 hour = 55 miles per hour Ex: 55 miles/1 hour = 55 miles per hour Distance = 55 miles Time = 1 hour

Graphing Speed: Distance vs. Time Graph Phoenix Denver

Question: Below is a distance vs. time graph for 3 runners. Who is the fastest? Leroy is the fastest. He completed the race in 3 hours.

How fast something looks like it’s moving all depends on your frame of reference.

Velocity: The speed of an object in a particular direction. Example: Example: An airplane moving North at 500 mph An airplane moving North at 500 mph A missile moving towards you at 200 m/s A missile moving towards you at 200 m/s

Question: What is the difference between speed and velocity? Speed is just distance/time. Velocity includes direction as well.

The rate at which velocity changes is called acceleration. When an object’s motion changes by slowing down, we call this deceleration. It can be: an increase in speed a decrease in speed a change in direction

Question: How can a car be accelerating if its speed is a constant 65 km/h? If it is changing directions it is accelerating

Momentum: How hard it is to start or stop an object. The more mass an object has, the more momentum it has. Ex: It’s harder to stop a 200 lb. linebacker than a 100 lb. ballerina The faster an object is moving, the more momentum it has. Ex: It’s harder to stop a car going 50 miles an hour than a car going 10 miles an hour.

Newton’s Laws of Motion Inertia: An object in motion tends to stay in motion and an object at rest tends to stay at rest unless acted upon by an outside force. Basically, objects tend to keep doing what they’re doing! Ex: Seatbelt!!! Acceleration: The greater the mass of an object, the greater the force needed to cause a change in its motion. Ex: Kicking a soccer ball makes it move. Kicking a bowling ball just hurts Equal and Opposite: For every action, there is an equal and opposite reaction. Ex: You and a friend jumping on a trampoline!

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