A cat lies on the floor.

Do Now: Please REWRITE the problems/answers (can bullet point) on loose leaf with enough detail that you remember the problem for an open notes quiz.

#1 #2A cat lies on the floor. Can you say that NO

FORCE acts on the cat? Or, is it correct to say that no net force (in other words, ZERO NET FORCE) acts on the cat?

EXPLAIN your answer (why/ how you answered the way you did etc.)

Consider 2 forces: one having a magnitude of 20N, and the other a magnitude of 12 N.What is the maximum

net force possible for these 2 forces?

What is the minimum net force possible for these 2 forces?

#1 #2

ANSWER: It is correct to say no net force. Both gravity (cat weight) and support force (thanks floor) act on cat.

They cancel to zero net force, but there are still forces!

ANSWER : MAXIMUM resultant occurs when they are parallel, in the same direction20N + 12N =

32 NMINIMUM resultant

occurs when they are in OPPOSITE directions 20 N – 12 N = 8 N

Exit Slips from last classTake yours back and review with peers… we will

go over answers in a minute!Also, take out your HW that was due today..

We are reviewing that, too…

•Make any necessary•corrections on yours!

An object in mechanical equilibrium is stable, without changes in motion.

A NET force is needed to change an object’s state of motion. If there is zero net force, then there is zero change in the object’s state of motionRemember from last class…

If an object is… At rest

OR Moving in a straight line at the same

speedThen the net force on that object is zero…there is no net force!

Remember from last class…

With ASSIGNED lab groups.. Please complete Ch. 2 POGIL #1: Spring Scales.

Check in w/teacher atWe will not go over as a class – it is your group’s responsibility

to pace accordingly and check in at Take the time to explain answers, but be EFFICIENT. There can

always be a pop quiz on material you are expected to complete!

Anything that you do not finished today is expected to be completed at home so that you are up to date next class. (However, you have more than enough time to complete this during class… having to complete work at home means you chose to allocate your time poorly.)

We are stopping with 5 minutes left in class to review HW and complete an exit slip.

Exit Slips!Take an exit slip and SILENTLY write your answers

(THREE questions!)Then, we will review answers on Powerpoint. When

the answer comes up, you will MAKE YOUR CORRECTIONS in a different color (or, circle them, etc…do something to make them stand out to me!)

These are not graded, so it’s ok if you make corrections!

To be turned in when done. These will be returned to you next class.

think!Suppose you stand on two bathroom scales with your weight evenly distributed between the two scales. What is the reading on each of the scales? What happens when you stand with more of your weight on one foot than the other?

2.3 Support Force

think!Suppose you stand on two bathroom scales with your weight evenly distributed between the two scales. What is the reading on each of the scales? What happens when you stand with more of your weight on one foot than the other?

Answer: In the first case, the reading on each scale is half your weight. In the second case, if you lean more on one scale than the other, more than half your weight will be read on that scale but less than half on the other. The total support force adds up to your weight.

2.3 Support Force

think!Two sets of swings are shown at right. If the children on the swings are of equal weights, the ropes of which swing are more likely to break?

2.5 Vectors

think!Two sets of swings are shown at right. If the children on the swings are of equal weights, the ropes of which swing are more likely to break?

Answer: The tension is greater in the ropes hanging at an angle. The angled ropes are more likely to break than the vertical ropes.

2.5 Vectors

think!In your own words, please describe why it is more difficult to do pull-ups with one arm, instead of 2. Include key terms we have used today.

You will not be given the answer for this today…Do your best

2.5 Vectors