Friday, September 2, 2011

Physics IB - IA Example: data collection and processing

!9# Physics IB - IA Example: data collection and processing

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For those who have difficulty writing their internships, this article allows for data collection and processing component to write a physics IB explain practical.

In principle, the practical calculations of the dynamics involved is allowed with the help of a machine, collisions with minimal friction. The objective was to examine the law of conservation of momentum.

Below is an example of this practice:

Data collection and processing:

Qualitative observations:

It 'wasnoticed that the metal ramp would be a bit 'after each shot and that if the ramp was adjusted heated, the plane because of the movement that changes shape metal. By adjusting the slider at the bottom of the ramp, the height can move the ramp so that the ramp approximately parallel to the ground, but as a vocation, railways, planes are likely to be influenced by the effects of gravity on the sides of the ramp. This would increase the uncertainties of this experiment, because theEffects of gravity would have taken hours.

Moreover, it records the acceleration of the infrared light SAILING readings during two distinct periods. The screen consists of two metal parts, which block infrared light and the time is blocked by the machine is used to calculate the acceleration. However, the two pieces of metal can reflect light and give back a part of the natural light in the room have on the reader. This may have added to the uncertaintyexperiment.

If the ramp has been set, so it was horizontal and the plane was placed in the middle, the plane rocked back and forth. The air rising from the holes of the ramp would push the brush against the edge of the wing and rear. Then push the air behind the shield against the edge of the wing and the brush.

After the collision of two gliders, it was found that the terminal velocity gliders' (separation after the collision) was similartheir initial velocity (before the collision). This indicates that the value should be the last trip similar to the value of the first lap.

After the string was cut between the slides, causing the magnetic force of repulsion between the magnets attached to them, go in different directions. It was found that the plane was heavier than the lightest shade slower. This is the same for the dynamism necessary (and as well as their directionsvice versa), since p = mv. If m is larger, v must be smaller to be the same for both p for gliders.

Raw data:

Note: The units are in SI units are converted to proper treatment.

There were two gliders, gliders A and B. A glider glider had a mass of 261G. Glider B had a mass of 309g. Let the uncertainty of half of the body, because the scales used to measure only possible up to 1 gram

A glider is always first and always on the left side Glider Bon the right side first. Let the direction of the velocity on the right side must be positive.

The uncertainty of the mass of each glider is + / - 0.5 grams, since the scale can be measured with precision at this level. 0.05 mm-1 - The uncertainty of the initial velocity and final would, in theory, be + /. This will be recorded in the raw data.

However, there are more uncertainties in this measurement is involved. It is not possible for the slope of the ramp, perfectly horizontal, soGravity has no effect. In addition, the air rising from the holes would also measure a few changes. The light reflecting off the metal plates can also influence the outcome. In addition, the recorder speed of light calculated from the length of the plates. The length of these plates is 100 mm + / - 0.5 mm. So there is much uncertainty over + /-0.05mms-1.

The uncertainty can not be quantified, but that would mean that the data can not be determined at 4significant digits. A rough estimate of the uncertainty will be 5mm-1. This is half the final digit of a measurement to 3 significant figures.

The correct number of significant digits will be used the processed data. For now, it will be left with four significant figures, since the raw data.

Experiment collision

Glider

Fair + / -0.05 (g)

u + / -5 (mms-1)

v+ / -5 (Mms-1)

A

261

1493

-836.0

B

309

-1186

780.0

Experiment magnetic repulsion

Glider

Fair + / -0.05 (g)

u + / -5 (mms-1)

v + / -5 (mms-1)

A

261

0.000

-280.0

B

309

0.000

230.0

Data processed: The data will now be converted to SI units and their uncertainties.

The mass of raw data must be converted to kilograms. Thus, the uncertainty isby + /-0.0005kg.

The speed of the raw data will be converted to ms-1. This will be only three significant digits, as explained above and the uncertainty is 0.005 ms-1.

Experiment collision

Glider

Fair + / -0.0005 (kg)

u + / -0005 (ms-1)

v + / -0005 (ms-1)

A

0.261

1.49

-0.836

B

0.309

-1.19

0.780

Magnetic RepulsionExperiment

Glider

Fair + / -0.0005 (kg)

u + / -0005 (ms-1)

v + / -0005 (ms-1)

A

0.261

0.000

-0.280

B

0.309

0.000

0.230

Momentum calculation:

Let A be the mass of the sail and its initial velocity uA mA and VA Let UB be its final speed and its top speed will be the mass of the BB B mB glider and its initial velocity

Be the first sweep of the screen of a PIA and his last race pfa. Leave the firstB PiB dynamic momentum of the sail and pfb are final.

Collision experiment:

pia = 1.49 = 0.389 = 0.261x Maua Ns

The uncertainty can be calculated by adding the uncertainties of the masses and the initial velocity:

Relative error = 0.002 mass = 0.0005/0.261 relative error of the initial velocity = 0.005/1.49 = 0.003 Total relative error = 0.005 or 0.5% absolute error = 0.005 x 0.389 = 0.002

Sun pious = 0.39 + / - 0.002 Ns

Using the same method, theother values ​​of momentum, and their absolute error can be calculated:

MAVA PFA = = (0.261 + / -0.0005) x (-0.836 + / -0.005) = - 0.22 + / - 0.002 Ns

PIB Mbube = = (0.309 + / -0.0005) x (-1.19 + / -0.005) = - 0.36 + / - 0.002 Ns

pfb mBvB = = (0.309 + / -0.0005) x (0.780 + / -0.005) = 0.24 + / - 0.002 Ns

Experiment magnetic repulsion:

Since UA and UB are both equal to 0, the first sweep of the A and B glider glider is equal to mu = 0 This is because most ex 0 = 0

PFA =MAVA = (0.261 + / -0.0005) x (-0.280 + / -0.005) =- 0.07 + / - 0.001 Ns

pfb mBvB = = (0.309 + / -0.0005) x (0.230 + / -0.005) = 0.07 + / - 0.002 Ns


Physics IB - IA Example: data collection and processing

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