Transcript Force and Motion in Two Dimensions

Warm-Up: October 30, 2015
• A 15.0 kg box is sitting at rest on a ramp. The
ramp is offset 15.0° from horizontal.
a) Draw a free body or force diagram for the
box.
b) Calculate the magnitude of each force acting
on the box.
Warm-Up: November 2, 2015
• A crate weighing 9.80x103 N is
pulled up a 37.0° incline by a force
parallel to the plane. If the
coefficient of kinetic friction
between the crate and the surface
of the plane is 0.750, what is the
magnitude of the applied force
required to move the crate at a
constant velocity?
Warm-Up: November 2, 2015
1.18x104 N
Force and Motion in Two
Dimensions
Section 5.3
You-Try #1
• A packing crate is placed on a 20.0°
inclined plane. If the coefficient of
static friction between the crate and
the plane is 0.650, will the crate slide
down the plane? Justify your
answer.
You-Try #1
Warm-Up: November 3, 2015
• A 5.0 kg wooden block is placed on
an adjustable wooden inclined
plane. 𝜇𝑠 = 0.58, 𝜇𝑘 = 0.40
a) What is the angle of incline above
which the block will start to slide
down the plane?
b) At what angle of incline will the
block then slide down the plane at
constant speed?
Warm-Up
You-Try #3
• Zgorb lives on a planet where
the acceleration due to gravity
is 8.50 m/s2. Zgorb places a
12.0 kg box on a ramp that is
20.0° off of horizontal. The
coefficient of static friction
between the box and the ramp
is 0.400, while the coefficient of
kinetic friction is 0.250. Assume
air resistance is negligible.
• Describe the motion of the box.
You-Try #3
You-Try #4
• A 175 kg crate on a horizontal floor
is being pulled by a rope pulling
with a force 10° above horizontal.
𝜇𝑠 = 0.50, 𝜇𝑘 = 0.30
a) How hard does the rope have to
pull in order to get the box to
start moving?
b) How hard does the rope have to
pull in order to keep the box
moving at a constant speed?
You-Try #4
Assignment
• Read Section 5.3
• Page 133 #33-37
• Page 135 #38-41
Warm-Up: November 4/5, 2015
• A block of wood is on a wooden ramp
that is 30.0° away from horizontal.
The block is pulled up the ramp at a
constant 1.00 m/s by a rope that is
parallel to the wooden ramp. The
tension in the rope is 25.0 N. The
coefficient of kinetic friction is 0.400.
• Is it possible to determine the mass
of the block?
• If so, what is it?
• If not, why not?
Warm-Up
You-Try #4
• A 175 kg crate on a horizontal floor
is being pulled by a rope pulling
with a force 10° above horizontal.
𝜇𝑠 = 0.50, 𝜇𝑘 = 0.30
a) How hard does the rope have to
pull in order to get the box to
start moving?
b) How hard does the rope have to
pull in order to keep the box
moving at a constant speed?
You-Try #4
Lab
• Work with your assigned group to:
a) Determine the coefficient of static friction
between a physics textbook and a calculator.
b) Determine the coefficient of kinetic friction
between a physics textbook and either a
horizontal table top or the floor.
• Allowed materials: rulers, meter sticks,
stopwatch (on phone), textbook, calculator
• After finishing, make a poster to present your
procedures and conclusions.
Lab Roles
• Leader – Collect and return supplies, keep
group on task, assist group members, fill in for
absent group members.
• Procedure recorder – Write down everything
that the group does to accomplish the
objective of the lab.
• Data/calculations recorder – Write down all of
the data that the lab group gathers and all
calculations done by the lab group.
• Presenter – Present procedures and results to
the class.
Lab Groups – Period 2
Group #
Leader
1
Nagelvoort,
Christopher
O, Christina
2
Obermiller,
Andrew
Bathard, Hallee
Gupta, Mihir
Clark, Nina
3
Waldman, Philip
Castaneda,
Ernesto
Rao, Ananya
Thomas, Zoe
4
Lodge, Grace
Imler, Carson
Bhushan, Somil
Lee, Rudolph
5
Yang, Jerry
6
Kapoor, Pia
Folkl, Julia
Nguyen, Haley
Laudenslager,
Alexis
7
Pro. Rec.
Data Rec.
Presenter
Padmanaban,
Sharma, Amitesh
Sneha
Nguyen, Wendy Hardisty, Sabrina Sandfer, Connor
Kwan, Crystal
Hagstrom, Erik
Jones, Cameron Wedge, Lauren
8
Andersen, Blake Brana, Jennifer Andersen, Blake
Kye, Johanna
9
Calkins, Nicholas Pennington, Julia Calkins, Nicholas Almond, Amber
Warm-Up: November 6, 2015
• A hockey puck is sliding across
horizontal frictionless ice. It then
moves onto a wooden floor, and
stops 2.34 s later, 4.81 m past the
wood-ice boundary. What is the
coefficient of kinetic friction
between the puck and the wood?
Warm-Up: November 6, 2015
Finish the Lab
Warm-Up: November 9, 2015
• A 35 kg block of wood is resting on
a wooden ramp that is 10° away
from horizontal. Rank the
following in order from greatest
magnitude to smallest magnitude:
A. Drag force
B. Friction force
C. Normal force
D. Weight
Warm-Up: November 9, 2015
Quiz: Chapters 4-5
• Thursday
• Review bookwork and worksheets
– Answers to 5.3 homework are on the web site
Projectile Motion Retake
• Thursday or Friday (your choice)
• During lunch or after school (your choice)
– If you do not finish during lunch, you will not get
extra time.
– 100 minute time limit after school
• Tell Mr. Szwast by end of Tuesday when you
will take the retake.
Finish the Lab
Warm-Up: November 10, 2015
• The weight of a 70.0 kg tightrope
walker standing on the middle of a
tightrope (equidistant from the two
ends) causes the rope to sag by 5.0°.
What is the tension in the rope?
Warm-Up: November 10, 2015