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Science Benchmark 3 Review. Motion, Laws of Motion, Machines, Work, Power, Energy, Energy Transformations. Motion. In order for there to be motion an object must move in relation to reference points. Speed. How much time it takes for an object to move a certain distance
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Science Benchmark3Review Motion, Laws of Motion, Machines, Work, Power, Energy, Energy Transformations
Motion • In order for there to be motion • an object must move in relation to reference points
Speed • How much time it takes for an object to move a certain distance • Formula v= d/t • Measured in m/s or km/hr etc • If you know both speed and direction then you know ---- • Velocity
Acceleration • The RATE at which velocity CHANGES • All these are acceleration : • Going faster • Going slower • Turning • This is why planets are accelerating – they are in a constant turn to form their orbit.
Laws of Motion • 1st - inertia – objects want to keep doing what ever they are doing • Books fly on floor when bus stops • You move forward when your parents slam on the car brakes
Laws of Motion • 2nd – acceleration – f=ma • A runner speeds up at the end of a race • A car slows down because they ran out of gas • It takes more force to stop a bus than a bicycle • To change acceleration – lower mass or use more force
Laws of Motion • Remember : • Mass is the amount of matter in an object • Weight is a measure of the pull of gravity on an object
Laws of Motion • 3rd – action and reaction – equal and opposite!! • When you jump down hard on a trampoline you will go high in the air • When a rocket is fired the gases push downward causing the rocket to go upward
Machines • There are six simple machines: • 1. Lever • 1st class • 2nd class • 3rd class
Machines • 2. wheel and axle
Machines • 3. wedge
Machines • 4. screw
Machines • 5. inclined plane
Machines • 6. pulley
Work • Work is using a force to move an object in the direction of the force • Formula w=fd • Measured in joules (J)
Power • How much work is done in a certain period of time. • The faster something does work the more power it has!! (less time) • Formula P=w/t • Measured in watts (w)
Energy • Energy is the ability to do work or to make a change. • There are two main categories of energy: • Potential • Kinetic
Potential Energy • Potential Energy is stored energy. • Food roller coaster
Kinetic Energy • Kinetic Energy is energy of motion
Energy Transformations • Energy is changed from one form to another but none can be created or destroyed! Match – chemical to thermal
Energy Transformations Food – chemical to mechanical
Energy Transformations Food – chemical to mechanical
Chemical Reactions Remember the only true proof that a chemical reaction has taken place is the formation of a new substance with new properties!!!
Chemical Formula 2Ca + O2 2CaO Reactants Product Remember to count atoms to see if balanced!
Good Luck!!!! Read well !!!!