2 classes left!
1
Rotational Dynamics
axis of rotation
Torque causes things to rotate
r2
What is precise relation between
torque and rotational motion?
F~2
Can generally be some number of
torques acting on object
~i = ~ri F~i
F~
3 classes left in semester!
1
Computing Torque
y
F~
Definition of torque vector
~ = ~r F~
r
Based on cross product of vectors
Result of cross product is always
orthogonal to original two vectors
Definition of cross product
for a
8 classes left in semester!
Still need to cover springs
1
Recall we are working on systems that
conserve mechanical energy
So far, weve worked with
gravitational potential energy
E =K +U
Kinetic energy
Potential energy
Ug = mgh
6 classes left in semester!
1
Work and Springs
Block of cheese attached to a
spring with spring constant k
How much work is required to stretch spring
from its rest length x0 to length x>x0?
Recall restoring force exerted
5 classes left in semester!
1
Finding center of mass
For a system of discrete point masses
N particles
~xcm
masses
mi
positions
~xi
i = 1, 2, . . . , N
m1 ~x1 + m2 ~x2 + + mN ~xN
=
m1 + m2 + + mN
In terms of components
xcm
Weighted averag
Tennis and Conservation of Energy
A tennis ball is hit 80 m/s at an angle of 30 from the top of a 10 m high
school. Ignoring air resistance, how fast is the ball travelling when it hits
the ground?
1
2
1
Ballistic Spring System
A bullet of mass m is fired
4 classes left in semester!
DKs office hours today 2:30-3:30PM
1
What is kinetic energy of a rotating object?
!
All points in object rotate with same
angular velocity
ri
But may have different speeds v=r
mi
Need to add up
7 classes left in semester!
1
Work and changes in kinetic energy
F~
Consider an object acted on by a single force
The object will accelerate and its kinetic
energy can change
~v
F~
Recall that acceleration can be a
chang
Physics 152 - Spring 2017
General Physics II
Section 1
Lecture 15 Monday, February 27
Lecture content
Demo
(light bulbs in series and parallel)
Resistance/conductance
Electric power
PHY152-S17-APP
Midterm 1:
Thu. Mar 2, 7-9 pm
(Ch 22-26, Hw 1-4)
Revie
Physics 152 Spring 2017
Magnetic Field Mapping Questions
(12 points)
1. In part 3.3 plot Vmax along the axis vs. x (distance from coil plane). (2 points)
2. Plot Vmax vs. the radial distance r from the center of the coil (x = 0). (2 points)
3. In part 3.4
Day3energyproblemset
1. The car shown in the picture below (mass = 998 kg) has just run out of gas while moving at a
speed of 15 m/s. Assuming that friction is negligible, will the car make it to the gas station if it
coasts the whole way? What is the spe
Forthesystemofthreeparticlesshown,whichhavemassesM,2M,and3Masindicated,whereisthe
centerofmasslocated?
a)
b)
c)
d)
Forthesystemofparticlesdescribedabove,findthexcoordinatexcmofthecenterofmass.Assume
thattheparticleofmassMisattheoriginandthepositivexaxisi
1)Twofrictionlessslidesareshapeddifferentlybutstartatthesameheighthandendatthesamelevel
asshownbelow.Youandyourfriend,whohasthesameweightasyou,slidedownfromthetopon
differentslidesstartingfromrest.Whichoneofthefollowingstatementsbestdescribeswhohasa
large
In the figure, what value of Fmax gives an impulse of 6.0Ns?
Answer Fmax = 1500 N
A student throws a 110 g snowball at 8.5 m/s at the side of the schoolhouse, where it hits and
sticks. What is the magnitude of the average force on the wall if the duratio
Section Number:
Team Number:
Force Plates and Impulse
Part 2 Collect data for the counter-motion jump
Materials
At each table you should have
A force plate / sonic ranger setup. The force plate is on the floor while the sonic ranger is
mounted on a pole.
In the figure, what value of Fmax gives an impulse of 6.0Ns?
Answer Fmax = 1500 N
A student throws a 110 g snowball at 8.5 m/s at the side of the schoolhouse, where it hits and
sticks. What is the magnitude of the average force on the wall if the duratio
Work energy problem set 1
1) Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following
statements is correct?
A) Both do positive work, but person X does four times the work of person Y.
B) Both do positive work
Section Number:
Team Number:
Part 1 Force Plates and Impulse Lab
Overview
This lab is based upon an exercise science lab at University of Southern California. Force
plates similar to the ones we will be using today are commonly used in physical therapy cl
Physics 152 Spring 2017
Charge, Current and Voltage Questions
(12 points)
1. In part 1.2.2 plot Voltage vs. Current for the resistor. Add a best fit line and determine the slope.
(1 point)
2. What does the slope in question 2 represent? Is this close to y
1
Chapter 2: Kinema0cs in One Dimension
2.1 Uniform Mo0on
2.2 Instantaneous Velocity
2.3 Finding Posi0on from Velocity
2.4 Mo0on with Constant Accelera0on
2.3 Free Fall
2.6 Mo0on on an Inclined Plane
2.7 Instantaneous Accelera0on
2
Free Fall
- A
Midterm Exam 1
Monday, February 27th
7:00-9:00PM
Covers material in Chapters 1, 2, 3 & part of 4: Everything up to Wed. Feb 22nd
Room assignment will be according the rst le5er(s) of your last name:
(will send out early next week)
Hasbrouck 126,
1
Chapter 2: Kinema0cs in One Dimension
2.1 Uniform Mo0on
2.2 Instantaneous Velocity
2.3 Finding Posi0on from Velocity
2.4 Mo0on with Constant Accelera0on
2.3 Free Fall
2.6 Mo0on on an Inclined Plane
2.7 Instantaneous Accelera0on
2
Posi0on and co
Physics 152 - Spring 2017
General
Physics
II
o
t
e
m
o
Section
1
c
l
e
W
Lecture 1 Monday, 23 January
Lecture topics
Introduction
General Information
Course content
Intro to electricity
PHY152-S17-APP
1
Instructor: Andrea Pocar
email: [email protected]
Electric Charge
If a 5.0 g nickel were made of pure nickel, what would be the total
charge of all of the nickels electrons? (Molecular mass of nickel is
58.7 g/mole. Atomic number of nickel is 28.)
1
Coulombs Law
Below is a model of positive charges in a
Physics 152 Spring 2017
RC Circuits Questions
(12 points)
1. For part 2.2.1 make a plot of VC vs. time. (1 points)
2. Using your plot in question 1, calculate the time constant . Use the values of R and C to
calculate the time constant, and compare it to