February 22/23, Week # 7NB-118

Learning Target: I will

• Define force and identify the correct units.

• Identify the types of friction

Homework:• Experiment Design

Essential Question:• Why is friction a force?

Agenda:

• Check HW (NB-115)

• Word wall

• Forces and friction notes

• Start homework

TO DO NOW:

• Turn in late hw

• Look at the word wall. Do you recognize any of the words?

Difficult Vs. Easy Topics

• Most students thought the speed and velocity problems were easier because of all of the practice. Most of these students thought the graphs were the most difficult.

• Those students who thought the problems were the most difficult, usually thought the graphs were the easiest.

Student Preparation

• Study more– With a partner

– Reviewing notes/notebook

• Pay attention in class

• Complete all of the homework

• Complete the notebook

Teacher Preparation: What you want

• Study guide (see learning targets, NB-98)

• Practice quiz (I don’t get the test early)

• Textbook activities

• Labs

• Whiteboard reviews

• Jeopardy game

• More examples

• Slower speech

HW: Page 273 #1-3, 7-10

1. Name three situations in which force is created. Describe the cause of the force in each situation.

2. Which of the following are units of force?

• Muscles create force swinging a racket

• Wind creates a force

• Massive objects (like planets) create a force called gravity

b. Newtons and pounds

HW: Page 273 #1-3, 7-10

3. Which is greater: a force of 10 N or a force of 5 lbs?

7. Name three devices or inventions which are designed to decrease friction.

8. Name three devices or inventions which are designed to increase friction.

• 1 pound= 4.448 N, so– 10 N ~ 2 lbs

– 5 lbs ~ 20 N

– Therefore, 5 lbs is bigger than 10 N

• Decrease friction: lubricants, ball bearings, magnetic levitation

• Increase friction: tires, nails, cleated shoes

HW: Page 273 #1-3, 7-10

9. If the force squeezing two surfaces together is decreased, the force of friction between the two surfaces will most likely:

• Think of pushing on a desk. If you push less (less force), there will be less friction

HW: Page 273 #1-3, 7-10

10. An astronaut in a space suit has a mass of 100 kilograms. What is the weight of this astronaut on surface of the moon where the strength of gravity is approximately 1/6 that of Earth?

• If you weigh 60 kg on earth, you would weigh 10 kg on the moon.

• Therefore, you divide 100 by 6 and get 16.7 kg on the moon.

Word Wall

• What words do you recognize?

• Talk to your partner. Did you both recognize some of the same words?

Glue these pages and add to table of contents:

• Weekly Planner #7 NB-118

• HW: page 273 NB-120

• Sample Experiment NB-121

• Label NB-119: Forces Cornell Notes

Forces Cornell Notes, NB-119

• A force is a push or pull, or any action that has the ability to change motion.

Question Answer

What is a force?

Answer: The four elementary forces are strong nuclear force, electromagnetic force, weak force, and gravity.

Forces Cornell Notes, NB-119

13.1 Units of force• When you measure

weight in pounds on a scale, you are measuring the force of gravity acting on the object.

• The word “pound” comes from the Latin word pondus, which means “weight.”

Forces Cornell Notes, NB-119

Questions Answers• Force is measured in

the units of pounds and newtons

• One pound of force equals 4.448 newtons.

Think, ink, pair, share

• What are four types of forces?

• How is force measured?

• Which is a greater force: a pound or a newton?

• Friction is a force that resists the motion of objects or surfaces.

Forces Cornell Notes, NB-119Questions Answers

• Friction is a force that resists the motion of objects or surfaces.

Essential Question:

Essential Question: How is friction a force? Remember: A force is a push or pull, or any actionthat has the ability to change motion.

• Friction depends on both of the surfaces in contact.• When the hockey puck slides on ice, a thin layer of

water between the rubber and the ice allows the puck to slide easily.

Forces Cornell Notes, NB-119

Forces Cornell Notes, NB-119

Question Answer• Five types of

friction are static, sliding, rolling, air and viscous

Design an experiment (HW)

Step 1:

• Think of different types of surfaces to test for the most/least friction: carpet, tile, wax paper, wood, cement, etc.

Step 2:

• Decide if you want to test rolling, static, or sliding friction.

Design an experiment (HW)Step 3:

• Decide what should be used to test the friction (marble, soup can, car, box, etc)

Step 4:

• Create a problem/question that best describes your experiment.– Which surface will create the most static friction

on a box?

– Which surface will create the least rolling friction on a marble?

Design an experiment (HW)Step 5:

• Create a hypothesis for your experiment– If aluminum is used then the rolling friction will be

decreased on the marble.

– If carpet is used then the sliding friction will be increased on the box.

Step 6:

• Fill in the lab handout front page