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# Physics Measurements

Physics, because it is a quantitative science, requires several measurements taken during experiments. Measurements are the assignment of numbers to objects or events. It is a cornerstone of most natural sciences, technology, economics, and quantitative research in other social sciences. It is important to be versed on the different units and recorded measurement techniques to ensure the answers are being recorded correctly.

Any measurement can be judged by the following meta-measurement criteria values, level of measurement, dimensions and uncertainty. These enable comparisons to be done between different measurements and reduce confusion. Increased precision through quantitative measurements is often preferred in cases of clear qualitative similarities of differences in order to aid in replication.

Measurements must be carried out with computational operations using the same units and conversion factors. It is also important to be aware of scalar and vector operations in detailed calculations. It is easy to be off by a multiplication factor in a mathematically heavy calculation which requires a detailed understanding in conversations and units.

## BrainMass Categories within Physics Measurements

### Vector and Acceleration

** Please see the attached file for the complete problem description ** Velocity and acceleration: consider a velocity vector given in standard unit vector form in rectangular Cartesian coordinates as ____ (please see the attached file). a. What is the acceleration at 2 seconds? b. What is the displacement at 5 seconds? c.

### Tension vs fundamental frequency

You are a roadie (a technical assistant) to a legendary pink guitar player Doyle Wolfgang von Frankenstein. During a concert, he breaks the low C string on his guitar. You are asked to restring it. When plucked it is supposed to have a fundamental frequency of f1=131Hz. When placed on the guitar, the string will have a length of

### Measurement, Percent Uncertainty and Significant Figures

Determine the percent uncertainty in theta and in sin(theta) when: a) theta = 15° +/- 0.5° answ: 3% and 3% (???) b) theta = 75° +/- 0.5° answ: 0.7% and 0.2% (???

### Measurement, Uncertainty and Significant Figures

a) What is the area, and its approximate uncertainty, of a circle of radius 3.4*10^4 cm? b) What, roughly, is the percent uncertainty in the volume of a spherical beach ball whose radius is r=2.86 +/- 0.09m?

### Spin 1/2 System: Pure and Mixed Ensembles

Consider a pure ensemble of a spin 1/2 system. Suppose <Sx>, <Sz> and the sign of <Sy> are known. Show how we may determine the state vector. Why is it unnecessary to know the magnitude of <Sy> ? Consider a mixed ensemble of a spin 1/2 system. Suppose [Sx], [Sy] and [Sz] are known. Show how we may construct the 2x2 densi

### Propagation of Uncertainties

A) According to theory, the period T of a simple pendulum is T=2&#928;&#8730;(L/g), where L is the length of the pendulum. If L is measured as L=1.40 +/- 0.01 m, what is the predicated value of T? b) Would you say that a measured value of T=2.39 +/- 0.01 s is consistent with the theoretical prediction of part (a)?

### Propagation of Uncertainties for a set of calipers

I have a set of calipers that can measure thickness of a few inches with an uncertainty of +/- 0.005 inches. I measure the thickness of a deck of 52 cards and get 0.590 in. a) If I now calculate the thickness of 1 card, what is my answer (including its uncertainty)? b) I can improve this result by measuring several decks to

### Tensor Products observables.

In the Hilbert space C^2 x C^2 (where x is used in all of my notation to mean the cross product) Consider the state vector: Psi = 1/sqrt(2) ( e_1 X e_2) + 1/sqrt(2) ( e_2 X e_1 ) (Part a) What is the probability that the measurement of q_3 X I gives the value -1 and how does the state vector change in

### Place these lengths in order of increasing size.

Put 1 for the smallest, 2 for the next smallest, etc. 1. 36,000,000 mm 2. 500 yards 3. 2140 inches 4. 1.3 km 5. 3240 feet 6. 455 meters 7. 5325 cm 8. 125 decimeters 9. 1 gigameter 10. 4 miles

### Problem on Pressure Measurements

A collapsible plastic bag contains a glucose solution. If the average gauge pressure in the vein is 1.34e+4 Pa, what must be the minimum height, h, of the bag in order to infuse glucose into the vein? Assume that the specific gravity of the solution is 1.05.

### Calculating the percent of error

What is the percent of error in the measurement 23+- 1 m^3?

### Buoyancy and Archmides Principle

Would you explain how to solve the following problem to the specified answer of 0.199? Please offer as much explanation as possible. What fraction of a piece of aluminum will be submerged when it floats in mercury?

### Water Pressure Gauges

The gauge pressure at a depth of 17 m in water is equal to what?

### Understanding Decimal Numbers

Question:0.0001993 is the same as? a. 19.93 x 10^5 b. 1.993 x 10^-4 c. 1993 x 10^7 d. 199.3 x 10^2 e. 1.993 x 10^4

### Understanding the Prefix

Question: What is the correct prefix to the fun-word "103-mockingbird". a. deci b. tera c. peta d. pico e. kilo

### What is the height in cm

What is the height in cm of the column of mercury for a mercury barometer whan the atmospheric pressure at a certain location is 1.02 atm? The density of mercury is 13.55g/cu m. a.73.7 cm b.77.6 cm c.75.3 cm

### Pressure Measurements

A piston (1) as shown in the figure has a diameter of 0.25 inches, and piston (2) has a diameter of 1.5 inches. In the absence of friction, determine the force F necessary to support the 500-lb weight.

### Water Flow in a U-Shaped Tube

A U-shaped tube, open to the air on both ends, contains mercury. Water is poured into the left arm until the water column is 13.1 cm deep. How far upward from its initial position does the mercury in the right arm rise? Please give your answer in mm. (NOTE: I've tried the answer 9.63 mm and it is incorrect.)

### Pascal's Principle and Blood Pressure Measuring

When a person's blood pressure is taken, it is measured on the arm, at approximately the same level as the heart. How would the results differ if the measurement were to be made on the patient's leg? Would the pressure be greater, according to the P2 = P2 + pgh equation? Thank you!

### Finding the centre of mass of a trapezoid

The figure shows a symmetric trapezoidal plate with a base of '2L'. The height and the top are each of length 'L' and the plate is of uniform density. Find the centre of mass of the trapezoid. P.S i have not included figure as scanner not working assuming know what it should look like. A rectangle with two triangles stuck on ea