Newton's Second Law

Newton's second law

By the end of this session; each student will be able to

1. Verify Newton’s second law experimentally through observing,and measuring some common forces that occur in our everydaylife e.g. gravity , friction & , and tension T.

2. Fit observed data with mathematically modeled physicalphenomenon.

3. Use a variety of physical measuring devices e.g. Stop watch,scale.

4. Estimate the uncertainty by applying the rules of StandardDeviation in the case of repeated measurements of a singlequantity and by employing the technique of Least-SquaresFitting in the case of experiment that involves the measurementof several values of two or more different quantities.

gf Sf Kf

Saturday, October 18, 2014

Course Student Learning Outcomes

2

5. Apply the technique of error propagation to estimate andmanipulate the uncertainty in directly and indirectlymeasurement of physical quantities.

6. Evaluate some uncertainty related quantities, namelyaccuracy and precision, confidence level, discrepancy, andsignificance of a discrepancy, and utilize them to determinethe sources of experimental errors, and to discuss how tominimize the uncertainties in the results.

7. Incorporate computer in measuring and analyzing theexperimental result.

8. Communicate scientific results in a written manner throughpresenting a word-processed report on the conductedexperiment.

Saturday, October 18, 2014

Course Student Learning OutcomesContinued…

3

Newton’s second law says that the

acceleration of an object is proportional to the

sum of the forces applied on that object

Fm

a

1

Saturday, October 18, 2014 4

Experimental setup


m1: T1 – Ffriction = m1a (1)

m2: m2g – T2 = m2a (2)


T2 – T1 = ma = 0a = 0

or

T2 = T1 (3)


Using Eqs. 1-3 we get

m2g – m1a – Ffriction = m2a

m2g– Ffriction = m2a + m1a

And thus 21

2

mm

Fgma

friction


Ffriction = 0

21

2

mm

gma


For an object moving with constant acceleration,

the equation of motion is given by

2

2

1attvxx oo

Divide both side of the equation by t, we get

t

at

t

tv

t

xx oo

2

2

1


atvt

x

t

xxo

o

2

1

This equation is of the form which is the equation

of straight line with slope S and intercept I

SxIy

aSlope2

1


Experimental procedure

1. Measure the mass of the chart m1 and estimate its error.

2. Measure the hanged mass m2 and estimate its error.

3. Hold the chart in a static position using the magnet (available

on the end of the track).

4. Set the sensor at a distance of about 20.0 cm from the end of

the chart (Be careful: take your measurement from the top

end that passes through the sensor and not the bottom end

which lies on the track. Talk to the instructor if in doubt). Do

not forget to estimate the error on your measurement.


5. Reset the counter and make sure the thread is not

impeded by anything (e.g. that it passes right through

the pulley and is not falling on the side).

6. Release the chart by pressing the trigger.

7. Record, in the table, the displayed time (use the first

counter only) and repeat this measurement three times.

8. Repeat steps 3-7 for the distances listed in the table

and fill it in.


Source

• http://www.nuffieldfoundation.org/practical-

physics/investigating-newtons-second-law-motion

• http://www.colorado.edu/physics/phys2010/phys2010NewLab

Man2001/2010labhtml/EXP1/EXP1LAB01.html

• Physics for Scientists and Engineers, 4th edition, Douglas C.

Giancoli, Pearson Education, Inc., Addison Wesley.

• Physics I Lab Manual, (Abdelouahab Abdesselam)


http://www.nuffieldfoundation.org/practical-physics/investigating-newtons-second-law-motion

http://www.colorado.edu/physics/phys2010/phys2010NewLabMan2001/2010labhtml/EXP1/EXP1LAB01.html

Newton's Second Law

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Transcript of Newton's Second Law