DW 12/4 1.Work is when an object moves in the _________ direction as the force applied. 2.If I pick up a book up 0.3 m with 6 N of force, how much work have a done on that book? W = FD 3.If a horse pulls a load using 4000j in 20 s, how much power did the horse use? P = W/T 4.Power is simply how fast or slow ____ occurs. 5.Why is carrying an object NOT work? Look at the definition to assist you.
How do we distinguish between the six simple machines?
Create flipbook out of 3 pieces of paper Label flaps: Inclined PlaneLever WedgeWheel and Axle ScrewPulley
Simple Machines Increase force Increase distance over which a force acts Change direction of force
Inclined Plane Also called a ramp Flat, sloped surface Less force is needed to move an object from one height to another using an inclined plane versus lifting the object Does NOT reduce the amount of work done it just changes Real world examples: stairs, switchbacks on a trail or road, wheelchair ramp
Wedge Incline plane that can be moved Often push materials apart One or two sloping sides Does NOT change the amount of work done Ex. Knife, axe, doorstops, teeth
Screw Incline plane wrapped around a cylinder Does NOT change the amount of work done.
Explain to your neighbor what all these machines have in common.
Brainpop Inclined Plane
Lever Any rigid rod or plank that pivots or rotates around a point called a fulcrum 3 classes according to location of fulcrum with respect to the input and output force PAGE 441 fulcrum Input force output force Ex. Baseball bat, scissors, seesaw, wheel barrow 1 st class (see-saw) 3 rd class (Baseball bat) 2 nd class (wheel barrow)
Brainpop Levers
Wheel and Axle 2 circular objects of different diameters attached so they rotate together Wheel has the larger diameter and the axle has the smaller diameter Examples: doorknob, water wheel, water spicket, Ferris wheel, steering wheel, ceiling fan
Brainpop Wheel and axle
Pulley p443 Consists of a grooved wheel with a rope or cable wrapped over it Changes direction of the force; when you pull down the object goes up Examples: raising a sail, raising a window blind, raising a flag
Brainpop Pulleys
House hold objectMachine or Machines in the object
Homework Science: WB 136
What tool would you use to separate a peel from a pear?
Which type of simple machine is used to harness geothermal energy, wind energy, and hydroelectricity?
When I push on a box, what force is working against me?
What type of simple machine is a slide?
If work = force times distance, how much work is done when you push a box with a force of 6 N two meters?
If the box I was just pushing continues on sliding after I release, is it work? EXPLAIN
What are the three simple machines that involve slanted surfaces?
Why are inclined planes used by movers and for disabled people getting into a vehicle?
Mechanical advantage MA = OF/IF The number of times the machine increases the input force
Inclined Plane The longer the inclined plane, the less force required to move an object.
Wedge Mechanical advantage increases as it becomes longer and thinner
Screw The tighter the threads the greater the “mechanical advantage”.
Lever Mechanical advantage depends on the location of the input force, output force, and fulcrum.
Wheel and Axle “Mechanical advantage” is equal to the diameter of the wheel divided by the diameter of the axle
Pulley Fixed pulley does not change the force you exert or the distance over which you exert it. Mechanical advantage is 1. Moveable pulley is when the pulley is attached to the object you are moving. Mechanical advantage is 2. Pulley system is made of multiple pulleys (fixed or moveable) and the mechanical advantage is found by adding.
How do I increase the mechanical advantage of an inclined plane and screw?
SS Test Study Material Urban, Suburban, and Rural characteristics Reading graphs and charts Reading a topographic map Physical maps have physical features, thematic maps are based on a theme, political maps show political boundaries and cities Urbanization causes and effects Population pyramids Vocabulary words