dw 12/4 1.work is when an object moves in the _________ direction as the force applied. 2.if i pick...

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 Plane Lever

Wedge Wheel and Axle

Screw Pulley

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

1st class (see-saw)

3rd class (Baseball bat)

2nd 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 object Machine or Machines in the object

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

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