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Force, Mass and Motion

Force, Mass and Motion . S8P3 Students will investigate the relationship between force, mass and motion. Determine the relationship between velocity and acceleration. Determine the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction.

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Force, Mass and Motion

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  1. Force, Mass and Motion S8P3 Students will investigate the relationship between force, mass and motion. Determine the relationship between velocity and acceleration. Determine the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction. Demonstrate the effect of simple machines on work.

  2. Vocabulary • Acceleration – the rate at which velocity changes. (speed or direction changes = acceleration) • Acceleration = • Example – Turn left onto another road or going down a hill in a car. • Negative Acceleration – acceleration in which velocity decreases • Example – when a car slows down • Deceleration - acceleration in which velocity decreases • Example – when a plane slows down to land Final velocity – starting velocity = m/s/s Time

  3. Vocabulary • Speed – rate at which an object moves (distance/time) (m/s) • Example – how fast a ball is thrown, car drives • Velocity – the speed of an object in a particular direction. (distance/time, direction) • Example – The car is driving 5 miles/hour north. • Final Velocity – final point at which velocity is measured • Example – when a car stops or passes an ending point. • Initial Velocity – beginning point at which velocity is measured. • Example – When a car starts or passes a beginning point.

  4. Vocabulary • Force – a push or pull. It has size and direction. (Newton (N)) • Example – pull open a door, pushing a car door shut. • Mass – the amount of matter in an object. (grams (g)) • Example – ping pong ball verses a marble • Motion – when an object changes position over time when compared with a reference point. • Example – running

  5. Vocabulary • Friction – a force that opposes motion between two surfaces that are touching. • Rubbing hands together, pushing a box on concrete • Inertia – tendency of all objects to resist any change in motion. • Example – ball will stay in motion unless another force acts upon it like gravity. • Gravity – a force of attraction between objects that is due their masses. • Example – ball falls to the ground. • Distance – the amount of space between two points. • Example – my house is 2 miles from your house

  6. Speed • How Fast???? • Have to know Distance an object moves and Time needed to travel that distance • Formula • Average Speed = Distance Traveled meters/second Time Traveled

  7. More about speed • Most objects CONSTANTLY change speed, so when you use the formula, it is the average speed. • If you drive to school, how often do you go 50 mph the entire way? Never.

  8. Velocity • Speed of an object in a certain direction • 2 cars were traveling at 50 km/sec on the highway for 2 hours. After 2 hours, one car was in Alabama and one car was in Florida. HOW??? • Opposite Directions! This is why know the direction is important when calculating velocity.

  9. More on Velocity • It changes when speed OR direction changes • You go from 20 mph to 50 mph, you change velocity • You go from 20 mph to 20 mph, but turn left you changed velocity. • 50 mph North shows velocity Why?

  10. Acceleration • The rate at which velocity changes, so… speed or direction have to change for the acceleration to change. • Deceleration: slow down • Change in speed or direction = (Final V – Initial V / Time) • Another word for Initial velocity is starting or original.

  11. Examine the table below for the acceleration of a car. You can see the acceleration of the car at any time is 5 m/s/s, so every second, the velocity of the car increases by 5 m/s.

  12. TOTD • Give one example of a change in acceleration • What info do you need to calculate velocity? (3 things) • What is the average speed of an object that travels over 100 meters in 20 seconds?

  13. Inertia Objects resist change in motion. If I am standing still, I will stay that way until…. This is called INERTIA Inertia is wearing a seat belt Example: a car is going 50 mph and comes to a sudden stop, you continue moving a 50 mph, unless something stops you… a seat belt or the dashboard.

  14. Mass VS Inertia • An object with a large mass has more interia. Changing the motion of an object with a large mass is harder than changing the motion of a smaller object. Which would you rather change the motion of? Moving Car or Rolling Soccer Ball

  15. Think about it??? • Which would you rather stop falling with your head? • Ping pong ball or marble • Which would you rather pull? • Tractor or wagon • Which would you rather swing? • Golf club or grand father clock pendulum?

  16. Friction • Affects the motion of an object • A force that opposes motion • Friction reduces the speed of an object and releases heat. • The amount of friction depends on: • Texture of the surface • Weight of the object being pushed or pulled • The amount of force.

  17. Gravity • Affects the motion of an object • Force of attraction • The earth is so large that ALL objects are attracted to it • Gravity depends on • Mass • Distance

  18. Balanced VS Unbalanced forces • Balanced forces – • net force = 0 • No motion • Total amount of force on an object • Unbalanced forces – • net force is greater than (>) 0 • Motion • Object acted on shows movement in one direction.

  19. Are these activities balanced or unbalanced forces?

  20. FORCE • A push or pull • Result in motion

  21. Mass • The amount of matter in an object. • NOT Weight of an object • Your mass is the same whether on Mars, Earth or the Moon. Your weight will change. • Ping Pong Ball vs. Marble • Feather vs. cotton ball • Stick vs bamboo

  22. A change in the position of an object with respect to time. Motion

  23. Simple Machines • Lever • Inclined Plane • Wheel and Axle • Wedge • Pulley • Screw

  24. Work • The application of a force to an object to move it a certain distance in the direction of the force. • Work = force X distance • W = F X D • Work is measured in joules (j)

  25. Input Vs. Output • Work you do on a machine is input work • You apply a force to the machine and move it through a distance • Work done by the machine is work output.

  26. How do Simple Machines make Work Easier? • It is a device that makes work easier by changing the size or direction of a force.

  27. Inclined Plane

  28. Wedge

  29. Screw

  30. lever

  31. Pulley

  32. Wheel and Axle

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