Percent Error In Gravity
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using a different procedure to check for consistency. Comparing an experimental
Percent Difference Physics Formula
value to a theoretical value Percent error is used when to use percent difference when comparing an experimental result E with a theoretical value T that is accepted
What Does Percent Difference Mean
as the "correct" value. ( 1 ) percent error = | T − E |T × 100% For example, if you are comparing your percent difference physics lab measured value of 10.2 m/s2 with the accepted value of 9.8 m/s2 for the acceleration due to gravity g, the percent error would be ( 2 ) percent error = | 9.81 − 10.2 |9.81 × 100% = 4% Often, fractional or relative uncertainty is used to percent difference definition quantitatively express the precision of a measurement. ( 3 ) percent uncertainty = errorE × 100% The percent uncertainty in this case would be ( 4 ) percent uncertainty = 0.0410.2 × 100% = 0.39% Comparing two experimental values Percent difference is used when comparing two experimental results E1 and E2 that were obtained using two different methods. ( 5 ) percent difference = | E1 − E2 |E1 + E22 × 100% Suppose you obtained a value of 9.95 m/s2 for g from a second experiment. To compare this with the result of 10.2 m/s2 from the first experiment, you would calculate the percent difference to be ( 6 ) percent difference = | 9.95 − 10.2 |9.95 + 10.22 × 100% = 2.5% Copyright © 2010 Advanced Instructional Systems, Inc. and North Carolina State University. | Credits
a Metric ruler, masking tape, a small and heavy weight, and a calculator Theory: Gravity exerts a force on every object. This force is proportional to the mass of the object. The proportionality constant is the acceleration of gravity "g." The gravity acceleration (g)
What Does Percent Difference Tell You About An Experiment
varies with change in elevation; however, for a few thousand feet above the Earth's surface, it percent error lab activity remains fairly constant. For an object undergoing a constant acceleration, the following equations of motion may be applied. (1) Vf = Vo+ a t
Percent Disagreement Vs Percent Error
(3) Vf 2 – Vo2 = 2 aX (2) X = [(Vf + Vo) /2]t (4) X = Vo t + ½ at 2, where: X = displacement, Vo = initial velocity, t = elapsed time, Vf http://www.webassign.net/labsgraceperiod/ncsulcpmech2/appendices/appendixB/appendixB.html = final velocity, and a = acceleration. For falling objects: a = g = 9.8 m/s2 . Procedure: The lab instructor will demonstrate the use of the spark timer and the spark sensitive paper. This is essentially allowing a strip of spark sensitive paper to fall freely between the spark gap while the spark timer is sparking at a frequency of 60. sparks per second. Each group of students should obtain a data tape. The tape will have a line of dots on http://www.pstcc.edu/departments/natural_behavioral_sciences/Web%20Physics/Experiment%2004.htm it separated by increasing distances between subsequent dots. The acceleration of falling motion can then be found by using the following methods: As soon as you get the tape, circle the points and number them as shown in Fig. 1. Method A: Find the acceleration by using the equation g = ( Vf – Vo ) /t . Vo may be calculated at a point near the beginning of the tape, and Vf at a point toward the end of the tape. The difference (Vf-Vi) divided by the corresponding elapsed time ( t ) will give the acceleration of the tape: g = (Vf – Vo) / t . Measure an initial distance, Xo, between 5 dots at the beginning of the tape and a final distance, Xf, between 5 dots toward the end of the tape. It is better to ignore the first few points that are very close to each other, because the relative error in measuring a small distance is high. Also, the last few points that may not be along a straight line should be disregarded. Calculate the initial and final velocities using the distances traveled ( Xo and Xf ) and the travel time for each of (4/60)s, that is, Vo = Xo / (4s/60) & Vf = Xf / (4s/60). Since the time interval between every two neighboring dots is 1/60 sec (the spark timer produces 60 sparks per second), the time interval corresponding to each of Xo or Xf is therefore,
inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/sciencu9/public_html/wp-content/themes/2012kiddo/header.php on line 46 Science Notes and ProjectsLearn about Science - Do Science Menu Skip to contentHomeRecent PostsAbout Science NotesContact Science NotesPeriodic TablesWallpapersInteractive Periodic TableGrow CrystalsPhysics ProblemsMy Amazon StoreShop Calculate Percent Error http://sciencenotes.org/calculate-percent-error/ 3 Replies Percent error, sometimes referred to as percentage error, is an expression of the difference between a measured value and the known or accepted value. It is often used in science to report the difference between experimental values and expected values.The formula for calculating percent error is:Note: occasionally, it is useful to know if the error percent difference is positive or negative. If you need to know positive or negative error, this is done by dropping the absolute value brackets in the formula. In most cases, absolute error is fine. For example,, in experiments involving yields in chemical reactions, it is unlikely you will obtain more product than theoretically possible.Steps to calculate the percent error:Subtract the accepted value from percent difference physics the experimental value.Take the absolute value of step 1Divide that answer by the accepted value.Multiply that answer by 100 and add the % symbol to express the answer as a percentage.Now let's try an example problem.You are given a cube of pure copper. You measure the sides of the cube to find the volume and weigh it to find its mass. When you calculate the density using your measurements, you get 8.78 grams/cm3. Copper's accepted density is 8.96 g/cm3. What is your percent error?Solution: experimental value = 8.78 g/cm3 accepted value = 8.96 g/cm3Step 1: Subtract the accepted value from the experimental value.8.96 g/cm3 - 8.78 g/cm3 = -0.18 g/cm3Step 2: Take the absolute value of step 1|-0.18 g/cm3| = 0.18 g/cm3Step 3: Divide that answer by the accepted value.Step 4: Multiply that answer by 100 and add the % symbol to express the answer as a percentage.0.02 x 100 = 2 2%The percent error of your density calculation was 2%. Calculate Percent ErrorLast modified: January 28th, 2016 by Todd HelmenstineShare this:GoogleFacebookPint