BIO Footwear Safety The American National Standards Institute (ANSI) specifies safety standards for a number of potential workplace hazards. For example, ANSI requires that footwear provide protection against the effects of compression from a static weight, impact from a dropped object, puncture from a sharp tool, and cuts from saws. In addition, to protect against the potentially lethal effects of an electrical shock, ANSI provides standards for the electrical resistance that a person and footwear must offer to the flow of electric current . Specifically, regulation ANSI Z41-1999 states that the resistance of a person and his or her footwear must be tested with the circuit shown in Figure 21-63. In this circuit, the voltage supplied by the battery is ɛ = 50.0 V and the resistance in the circuit is R = 1.00 MΩ. Initially the circuit is open and no current flows. When a person touches the metal sphere attached to the battery, however, the circuit is closed and a small current flows through the person, the shoes, and back to the battery. The amount of current flowing through the person can be determined by using a voltmeter to measure the voltage drop V across the resistor R . To be safe, the current should not exceed 150 µF. Notice that the experimental setup in Figure 21-63 is a dc circuit with two resistors in series—the resistance R and the resistance of the person and footwear, R pf . It follows that the current in the circuit is I = ɛ/( R + R pf ). We also know that the current is I = V/R , where V is the reading of the voltmeter. These relationships can be combined to relate the voltage V to the resistance R pf with the result shown in Figure 21-64. According to ANSI regulations, Type II footwear must give a resistance R pf in the range of 0.1 × 10 7 Ω to 100 × 10 7 Ω. Figure 21-64 Problems 103, 104, 105, and 106 103. • Suppose the voltmeter measures a potential difference of 3.70 V across the resistor. What is the current that flows through the person’s body? A. 3.70 × 10 -6 A B. 5.00 × 10 -5 A C. 0.0740 A D. 3.70 A
BIO Footwear Safety The American National Standards Institute (ANSI) specifies safety standards for a number of potential workplace hazards. For example, ANSI requires that footwear provide protection against the effects of compression from a static weight, impact from a dropped object, puncture from a sharp tool, and cuts from saws. In addition, to protect against the potentially lethal effects of an electrical shock, ANSI provides standards for the electrical resistance that a person and footwear must offer to the flow of electric current . Specifically, regulation ANSI Z41-1999 states that the resistance of a person and his or her footwear must be tested with the circuit shown in Figure 21-63. In this circuit, the voltage supplied by the battery is ɛ = 50.0 V and the resistance in the circuit is R = 1.00 MΩ. Initially the circuit is open and no current flows. When a person touches the metal sphere attached to the battery, however, the circuit is closed and a small current flows through the person, the shoes, and back to the battery. The amount of current flowing through the person can be determined by using a voltmeter to measure the voltage drop V across the resistor R . To be safe, the current should not exceed 150 µF. Notice that the experimental setup in Figure 21-63 is a dc circuit with two resistors in series—the resistance R and the resistance of the person and footwear, R pf . It follows that the current in the circuit is I = ɛ/( R + R pf ). We also know that the current is I = V/R , where V is the reading of the voltmeter. These relationships can be combined to relate the voltage V to the resistance R pf with the result shown in Figure 21-64. According to ANSI regulations, Type II footwear must give a resistance R pf in the range of 0.1 × 10 7 Ω to 100 × 10 7 Ω. Figure 21-64 Problems 103, 104, 105, and 106 103. • Suppose the voltmeter measures a potential difference of 3.70 V across the resistor. What is the current that flows through the person’s body? A. 3.70 × 10 -6 A B. 5.00 × 10 -5 A C. 0.0740 A D. 3.70 A
The American National Standards Institute (ANSI) specifies safety standards for a number of potential workplace hazards. For example, ANSI requires that footwear provide protection against the effects of compression from a static weight, impact from a dropped object, puncture from a sharp tool, and cuts from saws. In addition, to protect against the potentially lethal effects of an electrical shock, ANSI provides standards for the electrical resistance that a person and footwear must offer to the flow of electric current.
Specifically, regulation ANSI Z41-1999 states that the resistance of a person and his or her footwear must be tested with the circuit shown in Figure 21-63. In this circuit, the voltage supplied by the battery is ɛ = 50.0 V and the resistance in the circuit is R = 1.00 MΩ. Initially the circuit is open and no current flows. When a person touches the metal sphere attached to the battery, however, the circuit is closed and a small current flows through the person, the shoes, and back to the battery. The amount of current flowing through the person can be determined by using a voltmeter to measure the voltage drop V across the resistor R. To be safe, the current should not exceed 150 µF.
Notice that the experimental setup in Figure 21-63 is a dc circuit with two resistors in series—the resistance R and the resistance of the person and footwear, Rpf. It follows that the current in the circuit is I = ɛ/(R + Rpf). We also know that the current is I = V/R, where V is the reading of the voltmeter. These relationships can be combined to relate the voltage V to the resistance Rpf with the result shown in Figure 21-64. According to ANSI regulations, Type II footwear must give a resistance Rpf in the range of 0.1 × 107 Ω to 100 × 107 Ω.
Figure 21-64 Problems 103, 104, 105, and 106
103. • Suppose the voltmeter measures a potential difference of 3.70 V across the resistor. What is the current that flows through the person’s body?
Helicobacter pylori (H. pylori) is a helically-shaped bacterium that is usually found in the stomach. It burrows through the gastric mucous
lining to establish an infection in the stomach's epithelial cells (see photo). Approximately 90% of the people infected with H. pylori will
never experience symptoms. Others may develop peptic ulcers and show symptoms of chronic gastritis. The method of motility of H.
pylori is a prokaryotic flagellum attached to the back of the bacterium that rigidly rotates like a propeller on a ship. The flagellum is
composed of proteins and is approximately 40.0 nm in diameter and can reach rotation speeds as high as 1.50 x 103 rpm. If the speed
of the bacterium is 10.0 μm/s, how far has it moved in the time it takes the flagellum to rotate through an angular displacement of 5.00
* 10² rad?
Zina Deretsky, National Science
Foundation/Flickr
H. PYLORI CROSSING MUCUS LAYER OF STOMACH
H.pylori Gastric Epithelial
mucin cells
gel
Number
i
318
Units
um
H.pylori…
T1. Calculate what is the received frequency when the car drives away from the radar antenna at a speed v of a) 1 m/s ( = 3.6 km/h), b) 10 m/s ( = 36 km/h), c) 30 m /s ( = 108 km/h) . The radar transmission frequency f is 24.125 GHz = 24.125*10^9 Hz, about 24 GHz. Speed of light 2.998 *10^8 m/s.
Microbiology with Diseases by Body System (5th Edition)
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