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Created by the Faculty of the Mechanical Engineering Depart Created by the Faculty of the Mechanical Engineering Depart

Created by the Faculty of the Mechanical Engineering Depart - PowerPoint Presentation

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Created by the Faculty of the Mechanical Engineering Depart - PPT Presentation

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

velocity mass impulse cart mass velocity cart impulse initial lab time answer momentum impact combined negligible select force final

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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