View
216
Download
0
Category
Tags:
Preview:
Citation preview
Do now 1.If I am traveling at 60 mph
for 3 hours, how far can I travel?
2.How much force is needed to lift a 5kg object 8 m?
3.How much power is created when I use 26 Joules in 13 seconds?
Announcements• Test on Friday
▫ Test is posted on my Wiki if you would like to look at it.
▫ I will have something for you guys as a reward for focusing during the test
Agenda
•We are going to learn very quickly about a couple of things still remaining in the unit:
▫Simple Machines▫Potential and Kinetic Energy
6
Simple Machines
Ancient people invented simple machines that would help them overcome resistive forces and allow them to do the desired work against those forces.
7
Simple Machines
•A simple machine is a device that helps make work easier to perform
•“Simple” because there is only one working part.
8
Simple Machines
• The six simple machines are:▫ Lever ▫ Wheel and Axle ▫ Pulley ▫ Inclined Plane ▫ Wedge ▫ Screw
How does this effect the level of work?•While simple machines are simple and
lessen the workload, you are still doing the same amount of work.
11
The 3 Classes of Levers
•There are 3 types of levers:
•The class of a lever is determined by the location of the effort force and the load relative to the fulcrum.
12
Just so you can see…
To find the MA of a lever, divide the output force by the input force, or divide the length of the resistance arm by the length of the effort arm.
14
Wheel and Axle
•A wheel with a rod, called an axel, through its center: both parts move together
•Examples: Doorknob, pencil sharpener, bike
Inclined Plane
•An Inclined Plane is slanting surface connecting a lower level to a higher level
•Things move up or down it
•Slide, stairs, ramp, escalator, slope
Pulley
•A pulley is grooved wheel with a rope or cable around it
•Moves things up, down, or across
•Curtain rod, tow truck, mini-blind, flag pole, crane
17
Wedge•The wedge is a modification of the inclined plane. Wedges are used as either separating or holding devices.
19
Screw
•The screw is also a modified version of the inclined plane.
• It is considered a sixth simple machine
Energy
• Energy: how much work something can do
• measured in Joules, J• -Energy can change forms
II. Potential Energy
• Potential Energy: energy of position or “stored energy”
• Potential energy depends on mass and height.
II. Potential Energy
The person has more potential energy at the top of the stairs than at the bottom.
III. Kinetic EnergyWhich has more kinetic energy, the regular car or the race car?
The race car has more KE because it has a higher velocity.
III. Kinetic Energy
Which would hurt more, getting hit by a 15 foot wave or a 2 foot wave?
The bigger wave would hurt more because even though they travel at the same speed, the bigger wave has more mass.
Can you think of any more examples of kinetic energy?
Group Practice
•Write down 4 examples of potential energy, 4 examples of kinetic energy on your index cards
•Pass the cards to another group•Place the cards you receive in the right
category on your sheet•When you’re done, get your Independent
Practice!
Recommended