Finding the best operating conditions

That was the goal today. What setup will lift the most number of washers? Tomorrow we will share our obseravtions and determine the maximum force the motor can lift.

QUIZ UPDATE: Due to the impending snow storm Wednesday, the quiz will now be a take home quiz. Quizzes will be issued tomorrow and will be DUE THE DAY WE RETURN TO SCHOOL. If you do not return the quiz on the day we return, you will be issued a time either afterschool or during lunch next week to take the quiz (again). I am not accepting quizzes past the date we return (if you are absent then yes I will accept).

Sliding friction

The three investigations done in class this week has led us to discover that:

• The force of sliding friction depends on the type surface it is moving across.
• The force of sliding friction increases as the weight increases.
• The force of sliding friction does not depend on the surface area of the block in contact with the surface.

You used a spring scale to measure the force that counterbalanced the frictional force. This was evident when you pulled on the scale at a steady rate. Your effort force is equal to and opposite the frictional force. (Newton's Third Law!)

We also discussed another type of friction- air resistance. Keep in mind the variables you tested in class would affect objects differently in the air. (Surface area matters when you are flying through the air!)

Reminder: HW list and lab reports are due tomorrow!

Collecting Data on Friction

We used the class period today to collect data on the assigned variable and friction. You now have all the info needed to complete your lab report. All lab reports are due by Friday. Any lab report received next week will lose points each day.

Need something to do this Friday?

Then come check out the district staff talent show at the PAC at 7pm! Last year's talent show was a hit and this year should be also! Performing again on stage will be HOLD FOR DISMISSAL. The staff cover band is back with 3 new songs. Tickets are $4 for students and $5 for adults. Money collected will benefit Project Graduation.

Investigating friction

Our investigation on forces led us today to think about how the effort force will change due to surface type, weight of the load, and surface area. Groups were assigned one set of variables to test. In class you began writing your lab report for this lesson. Tomorrow, you will conduct the lab and finish the lab report.

All lab reports will be given a test grade and are due no later than FRIDAY, FEBRUARY 5!

Also due Friday ~ HW list for this week.

Net force

Concepts covered today:

• Reviewed properties of gravity
• Calculated net force on an object

HW lists have been given out for the week. Reminder that all 4 assignments are due by Friday, February 5.
Lost your homework list? Check out the link in the upper right hand corner!

Gravity

By now, you should understand that mass and weight are directly related. MASS measures the amount of matter in an object and WEIGHT measures the pull of gravity on an object. So, in order to lose weight you must decrease your mass. This also explains why your weight WILL CHANGE in space but your mass STAYS THE SAME.