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# Lab 3 Newtons law of motion 78.5 out of 85.docx

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Arizona State University

Physics

PHY 122

Dolenko

Spring

Description

Lab 3: Newton’s Law of Motion
T.A:
Monday at 2:00 p.m
Abstract:
This experiment was conducted in order to demonstrate Newton’s second law of
motion, to experimentally determine the acceleration of gravity and to experimentally
find the mass of the object. In the experiment masses (in increments of 10 grams
beginning from 10 up to 50 grams) were added to a string attached to a cart and the
speed of the cart was recorded using a motion sensor. In part two, the cart was given
an initial push along with the masses added to the cart as well. Therefore, 510 +/- *90
m
grams G experimental¿−0.3 2 and the discrepancy between the actual acceleration
s
due to gravity and the recorded acceleration of gravity was 6.89%. The results verify
Newton’s law that the sum of the forces has a linear relationship with acceleration and
mass and the experimental acceleration by gravity is close to what it was expected to
be. The biggest challenges of this experiment were overcoming individual error as the
error seemed to be large in certain trials. Objective:
The objective is to validate Newton’s second law by subjecting a force to a cart on a
nearly frictionless surface, to calculate the experimental mass of the cart using a graph
of the acceleration vs. net force, and to give an initial push to the cart to calculate the
experimental value for the acceleration of gravity.
Equipment:
The equipment used in this lab was a cart on a nearly frictionless surface with a string
attached that wrapped around a pulley and at the end of the pulley was an ‘s’ shaped
hook that ten gram masses were added to, and a motion sensor was used to record the
speed of the cart.
Procedure:
First the cart was placed on the nearly frictionless track and four ten gram masses were
add to the cart and one ten gram mass was added to the hook on the other end of the
string. The motion sensor was used to record the speed of the cart generated by the
mass on the end of the string. For the second trial, two of the ten gram masses were
added to the hook and three masses were added to the cart. For the third trial three
ten gram masses were added to the hook and two masses were added to the cart. The
fourth had four ten gram masses added to the hook with one mass added on the hook
and the fifth trial had all five masses added to the hook. For part two, the cart was given
an initial push and the trials were repeated while varying the masses on the hook from
10 to 50 grams.
Results:
Recorded mass of cart = 504.6 grams.
Mass experimental is 510 +/- *90 grams *answer was truncated G =9.1+¿−0.
experimental 3
% discrepancy in G = 6.9%
Data Analysis:
Expected value of mass = 504.6 grams
Mass experimental average−∆ M
Mass average 1 ¿
slope
slope*= slope from graph 1 of acceleration versus net force 1 in data analysis
Mass :
Example Calculation of average
Mass = 1
averag1.949 .513
∆ M Mass average xaverage ∆x
Calculating given , and : ∆ M ∆x ∆M ∆x
= =
Massaverage average Mass averageaverage
*Result used in discussion was truncated to 90 grams
Example Calculation for findingM :
∆ M ∆x .363
Mass = X ∆M=.513∗( 1.949) .095kg*
average average
Therefore, mass experimental is 510 +/- *90 grams
* ∆ M was truncated rather than rounded
G experimenaverage−∆G
meters
G averagwas found to be 9.13 second2 by plotting gravity vs. itself on graph 2
∆G
Calculating :
G
∇G= average
√ n
*n= number of trials
Sample Calculation for ∆G:
∆G= 9.134=.268
√5 m
Therefore, Gexperimental+¿−0.3 2
s
% discrepancy of g
∣gexperimenttheoretical
% =

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