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CH 4
by:Ana María, download !, 4d58c18c81cd3953373574e549decc19, download…
CH 4
by:Ana María
Section 1
Summary:
-Work has a different meaning in science. Work is described as the force applied through a distance.
-When force and motion are parallel: Work=applied force x distance
-When they are perpendicular: Work= 0
-The only way we do work is if we apply a force on an object and move it.
-Machines are useful because they change the way we do work. Machines either increase the speed, change direction, or change the force.
-Simple machines work with only one movement (ex: levers or pulleys)
-Compound machines are a combination of various simple machines.
-Efficiency of machines is the ratio of output work to input work; it is never 100%.
-Mechanical advantage of machines is the ratio of output force to input force.
Real Life Examples:
1) I am doing work because I pushed a box with 20N for 4m.
2) A wedge in a knife will change the direction of force because as you apply force downward the knife will apply an outward force to cut.
Formulas:
-Work (joules)= applied force (newtons) x distance (meters)
-Efficiency(%)=output work (joules)/input work (joules) x 100
-Mechanical advantage= output force (newtons)/ input force (newtons)
Section 2
Summary:
-Energy is having the ability to cause change or to do work.
-Systems are anything near us which we can imagine a boundary (it can be one thing or various)
-Energy can be found in different forms such as mechanical energy, electrical energy, chemical energy, and others.
-Kinetic energy is energy due to motion or movement.
-Potential energy is the enrgy which is stored due to the interactions objects have between each other.
-Gravitational potential enrgy is the energy that is present when there is gravitational force between objects.
Real Life Examples:
1) When my dog is running she has kinetic energy.
2)When my book of 1kg is on my shelf that is 2 m tall the gravitational potential energy is 19.6.
Formulas:
Kinetic energy (joules)=1/2 mass (kg) x [speed(m/s)]2 (squared)
Gravitational potential energy (joules)= mass (kg) gravity (N/kg) height (meters)
Section 3
Real life Examples:
1)If I thow a ball into the air it will follow a curved path or projectile motion. This means that GPE and kinetic energy will transform back and forth between each other.
2) The lamp in my room used electrical energy and the turned it into light energy.
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Summary:
-The law of conservation of energy states that energy will never be created or destroyed.
-Instead, energy transforms.
-Mechanical energy is the addition of kinetic energy and potential energy (only gravitational PE and elastic PE)
-Energy transforms when objects fall, when there is projectile motion, and on swings.
-Friction and air resistance can change mechanical energy into thermal energy.
-Other transformations might involve other forms of energy such as electrical energy and chemical potential energy.
-Power is defined as the rate at which energy is converted.
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All infromation from E-Book
E-book citation: McGrawhill. “Physical Science 2017.” ConnectED, 2017, connected.mcgraw-hill.com/mhelibs/projects/ebook-reader/1.13.0/player-reflowable.html.