Motion unit Review

Speed-distance travelled over time. Measured usually in m/s

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Velocity-Speed in a given direction.

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Acceleration-Change in velocity over time. Caused by change in speed or direction​. Measured in m/s²

​Some text here about the topic of discussion.

​Kinematics

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The slope of a distance-time graph gives velocity.

The slope of a speed-time graph gives acceleration!​

-Balanced forces are equal and act opposite to each other giving no motion.

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-Unbalanced forces have a net value of more than 0 so causes motion.​

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​-All object with a mass has a force of gravity. The larger the mass and the closer the objects, the greater will be its force of gravity (hence we are attracted to the earth and not each other).

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-Objects of similar size/shape will experience similar force of gravity regardless of mass and fall from same height at same time.

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-If same mass, but different surface area, objects will fall at different rate. Smaller first

-Force = mass multiplied by the acceleration​

Forces and Gravity

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-First law also called law of Inertia.

-Inertia is the tendency of a body to resist change​.

-The greater the mass, the more force needed and smaller the acceleration​.

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-Forces act in pairs that are equal in size but opposite in direction​

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-Work is the use of force to move an object over a distance in the direction of the force.

-Work =Force multiplied by distance.

-Work is measured in Joules.

-Simple Machines make work easier by either changing direction of applied force, reducing the force needed or increasing distance over which work is done​.

​-Examples: Fixed pulleys change direction, inclined planes, screws, wedges and levers increase distance, movable pulleys multiply force applied.

Work and Simple Machines

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​-This is how many times the machine multiplies the input force to make work easier.

-MA= Output force/input force​

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​- Movable pulleys, to get input force, find the MA by counting the supporting ropes (or number of movable pulleys) then divide the mass by that number​.

-Levers, MA increases if fulcrum is closer to load than the effort force applied.​ M

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​Mechanical Advantage