Download Science Starter

Science Starter
• Take out your yellow sheet and complete next 2
problems
• Take the first 5 minutes and try to complete them on
your own!!
• Place on your desk: Modeling Energy (both HWs),
Conservation of Energy Lab
AP EXAM SIGN UP
DEADLINE FOR SUBMITTING PAPER WORK
EXTENDED TO TODAY 4pm
Today’s Agenda
• Science Starter- Warm Up Review Packet Final
• Energy & Work
• Energy & Non-conservative Forces Lab
• Davidson NEXT
• Unit 4 Summary
Lesson Essential Question
What does it mean for energy to be conserved?
• Kinetic Energy is energy of motion
Energy & Work
K=1/2(m)v2
• Gravitational Potential Energy
Basic Energy Model
Ug=mgh
• Work: transfer of energy by
mechanical forces (W=Fdcosθ) • Elastic Potential Energy
2
U
=1/2(k)x
s
• When work is done on a
• Thermal Energy (friction)
system, the system’s total
energy changes by the amount
ΔEth = fkΔx
of work done
• If a system is isolated and friction is
present then…
ΔE=ΔK+Δug+…=W
Kf+(Ug)f+(Us)f+ΔEth = Ki+(Ug)i+(Us)i
• If a system is isolated, W=0
Energy & Non-Conservative Forces Lab
• Problem: Determine the amount of energy dissipated by friction
in a system consisting of a modified Atwood machine (.5 meters)
• Materials: Wood block, wood board, frictionless pulley, string,
meter stick, mass, mass hanger
• What information are you given?
• Coefficient of friction: u=0.4
• Mass of block: 0.7 kg
• Lab must include: procedures, system, bar charts, mathematical
representations, data table and analysis, conclusion, and
explanation of any errors
Modified Atwood Machine (50 minutes)
Davidson NEXT
• Take a computer and go to the following website:
edge.edx.org
• Login using your username you created and a password
• You should see a course for Physics 1
• When you open the course go to Rotational Motion
• Read Overview & Objectives, continue on through the
module in order
• Can do alone or in partners!
Summary & Homework
• Complete the conservation of energy problems
• Watch intro to momentum video (Khan Academy)
https://www.youtube.com/watch?v=XFhntPxow0U
• Complete Lab Report (same rubric as last lab)
Checking Our Work
• Experimental Values:
• What you find in the lab
• Should have found velocity, height, distance moved, and masses of moving pieces
• Actual Values:
• What the numbers should be
• Check your work with the following equation
Wfriction=ΔE= fkΔx=ukmgΔx=(0.4)(0.7 kg)(9.8m/s2)(0.5m)=1.372 J
Calculating Percent Error