MECE 102 Engineering Mechanics Lab A First Year Course in Newtonian Mechanics Experimentation and Computer Tools MECE102 Course Grades Exam 1 Performance Average Grade 70 ID: 580356
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Slide1
Created by the Faculty of the Mechanical Engineering Department in the Kate Gleason College of Engineering at RIT
MECE
102: Engineering Mechanics Lab
A
First Year Course
in
Newtonian
Mechanics, Experimentation,
and Computer
ToolsSlide2
MECE-102 Course Grades
Exam #1 Performance
:
Average Grade = 70%
Max Grade = 100%Slide3
Week 7 Lecture
Impulse and Momentum
We will study:
the impact of two carts
moving along a horizontal paththe tradeoff
between
Impulse
and
Momentum
that
occurs during the
impact of the carts
We will be using the
Ultrasonic Transducer
to determine distances travelled, velocities and momentums of the moving carts.Slide4
iCLICKER:
The week 7 Lab Experiment studies the relationship between
Impulse
and
Momentum of a system.
Which one of the following
is the definition of Impulse?
Select your Answer:
The distance integral of force.
The time integral of force.
The time derivative of acceleration.
The time derivative of velocity.
None of the above.Slide5
iCLICKER:
The week 7 Lab Experiment studies the relationship between
Impulse
and
Momentum of a system. Which one of the following
is the definition of Impulse?
Select your Answer:
The distance integral of force.
The time integral of force.
The time derivative of acceleration.
The time derivative of velocity.
None of the above.Slide6
iCLICKER: Which of the following are
units of Impulse?
Select your Answer:
[kg m/s]
[kg m/s
2
]
[N s]
[N m]
None of the aboveSlide7
iCLICKER: Which of the following are
units of Impulse?
Select your Answer:
[kg m/s]
[kg m/s
2
]
[N s]
[N m]
None of the aboveSlide8
FORMULATE: State the Known Information
Determine the
speed
of
a vehicle
with mass
m
1
after its collision and attachment to a vehicle of mass
m
2
.Estimate the work done during the collision process by comparing the theoretical speed versus the observed speed of the combined vehicles, m1 + m2 .Slide9
FORMULATE:
Identify the Desired InformationSlide10
iCLICKER: For our Week 7 experiment, which one of the following assumptions is
FALSE?
Select your Answer:
Air resistance is negligible.
Friction force is negligible.
Mass of the system being analyzed is constant.
Heat Transfer between the vehicles and track is negligible.
Elastic Spring Energy is negligible.Slide11
iCLICKER: For our Week 7 experiment, which one of the following assumptions is
FALSE?
Select your Answer:
Air resistance is negligible.
Friction force is negligible.
Mass of the system being analyzed is constant.
Heat Transfer between the vehicles and track is negligible.
Elastic Spring Energy is negligible.Slide12
FORMULATE: Identify AssumptionsSlide13
Figure 7.1: Schematic Diagram of
a first car colliding with and attaching to a second cart.
CHART
:
Schematic
DiagramSlide14
CHART: Free Body DiagramsSlide15
CHART: Data Tables
Each
row in the
STATE TABLE
corresponds
to one unique position
as the cart moves
along the
track.
This Lab Experiment will
analyze the impact of the two carts
along a horizontal surface where we define our elevation datum, z = 0.Slide16
CHART: Data Tables
The
PROCESS Table
describes the
exchange of energy,
work, heat
,
Impulse and Momentum as the system moves
between states.
For this experiment
we are interested in the Impact “Process”
which takes place starting at an initial state, i , and ending at a final state, f .Slide17
EXECUTE: Recall the Governing EquationsSlide18
EXECUTE: Recall the Governing Equations
Newton’s 2
nd
Law states the “
The net external force acting upon a body is equal to the time rate of change of the linear momentum of the body.
”
Separating the differential and integrating between an initial time,
t
i
, and a final time,
tf gives:Slide19
EXECUTE: Recall the Governing Equations
Recall that Impulse is defined as “
The integral of force over time.
”
This generalized version of Newton’s 2
nd
Law allows us to predict the motion of a system of
interacting
bodies.Slide20
iCLICKER: Based on the concepts of Impulse and Momentum from Week 7, we should expect that the
velocity of cart 1 just
prior to impact
will be
greater than the velocity of the combined carts
after
impact
.
Select your Answer:
True
FalseSlide21
iCLICKER: Based on the concepts of Impulse and Momentum from Week 7, we should expect that the
velocity of cart 1 just
prior to impact
will be
greater than the velocity of the combined carts after impact
.
Select your Answer:
True
FalseSlide22
EXECUTE: Recall the Governing Equations
Analysis of the cart FBD’s confirms that action and reaction forces between the 2 carts are equal and opposite
(
Newton’s 3
rd
Law
). Applying the previous Assumptions to the analysis generates the following equations:Slide23
EXECUTE: Recall the Governing Equations
Analysis of the Momentum equations associated with the initial mass
m
1
and the final combined mass (
m
1
+
m
2
) gives:
Solving for the final velocity of the combined mass (
m
1
+
m
2
) gives:Slide24
Consider the following Problem ………Slide25
Given a cart with initial mass,
m1
, determine the mass,
m
2
, of a second cart that generates a final velocity,
V
f
, of the combined masses (
m1+ m2) equal to
of the initial velocity,
V
i
.
Consider the following
Problem
………Slide26
Given a cart with initial mass,
m1
, determine the mass,
m
2
, of a second cart that generates a final velocity,
V
f
, of the combined masses (
m1+ m2) equal to
of the initial velocity,
V
i
.
Consider the following
Problem
………
Answer:
m
2
= 7
m
1Slide27
Figure 7.3: Apparatus and two body impact within the
field of view of
an ultrasonic
transducer
Lab Experiment Set-upSlide28
Now let’s talk about Asteroids …
http://news.cnet.com/8301-11386_3-57564621-76/europes-space-agency-kicks-off-asteroid-collision-mission/Slide29
Homework
Prior to LAB tomorrowRead
section
7.2
of the textbookWatch LAB Videos
Complete
the on-line LAB quiz in
myCourses
Attempt to solve all assigned chapter problems in your logbook before RECITATION.
WEEK
7
Problem Set: From Section 7.5: Problems 1, 10, 17, 18, 19 Lab Report is due Monday by 6pm!The Scribe must upload the LAB REPORT to the myCourses Dropbox
.Slide30
Questions?Slide31
Given a cart with initial mass,
m1
, determine the mass,
m
2
, of a second cart that generates a final velocity,
V
f
, of the combined masses (
m1+ m2) equal to
of the initial velocity,
V
i
.
Consider the following
Problem
………Slide32
Given a cart with initial mass,
m1
, determine the mass,
m
2
, of a second cart that generates a final velocity,
V
f
, of the combined masses (
m1+ m2) equal to
of the initial velocity,
V
i
.
Consider the following
Problem
………
Answer:
m
2
= 3
m
1