scholarly journals The air-resistance to a runner

1928 ◽  
Vol 102 (718) ◽  
pp. 380-385 ◽  
Keyword(s):  
Short Distance ◽  
Relative Velocity ◽  
Leeward Side ◽  
Maximum Speed ◽  
Total Resistance ◽  
Projected Area ◽  
Air Resistance ◽  
Eddy Formation ◽  
Maximal Effort ◽  
Original Treatment

The resistance of the air to the motion of a badly stream-lined body, in which the negative pressure on the leeward side, due to eddy formation, is appreciable, may be roughly 0·6 pv 2 A, where v is the relative velocity, p the density of the air, and A the projected area on a plane perpendicular to the direction of motion. In a recent paper Furusawa, Hill and Parkinson (1) have examined the motion of a runner making a maximal effort over a short distance, on the assumption that the air-resistance is negligible when compared with the resistances inherent in the muscles and limbs of the runner himself. This assumption is nearly, but not strictly, true, the air-resistance to a man running in still air at maximum speed being of the order of 2 to 5 per cent, of the total resistance which his muscles have to overcome. In view of the importance of fractions of a second in Model of runner used in wind-channel experiments; spindle visible at top. sprint “records,” and of the well - known influence of a following or head-wind in diminishing or increasing the time in such races, the original treatment of the dynamics of sprint-running may be modified to take account of the air-resistance as follows.

LIKE TRAJECTORIES OF THE BODY MOTION IN THE MEDIUM, THE RESISTANCE OF WHICH IS PROPORTIONAL TO THE SQUARE OF RELATIVE VELOCITY

2020 ◽  
pp. 71-76
Author(s):  
V.A. Chernovolov ◽  
◽  
L.V. Kravchenko ◽  
S.A. Sherstov
Keyword(s):  
Initial Velocity ◽  
Relative Velocity ◽  
The Body ◽  
Body Motion ◽  
Initial Angle ◽  
Air Resistance ◽  
Simultaneous Change

The force of gravity and the force of air resistance affect a particle thrown at an angle to the horizon with an initial velocity. In the calculation of wind protection and distribution devices, it becomes necessary to reduce the differences in trajectories when changing the type of fertilizer. There are two possibilities for simple adjustments. First, you can try to increase the throwing speed of fertilizers with a high windage factor. Secondly, the initial throwing angle can be adjusted. However, it is not possible to achieve alignment of the trajectories by adjusting the throwing angle. The smallest difference in trajectories was obtained by combining the simultaneous change in the initial angle and throwing speed. By simultaneously adjusting the initial angle and initial throwing speed, it is possible to almost match the trajectories of particles with different wind ratios, which is useful when working with a distributor

scholarly journals Comparative Study of Air Resistance with and without a Superstructure on a Container Ship Using Numerical Simulation

2020 ◽  
Vol 8 (4) ◽  
pp. 267 ◽  
Author(s):  
Jun Seok ◽  
Jong-Chun Park
Keyword(s):  
Numerical Simulation ◽  
Empirical Formula ◽  
Direct Calculation ◽  
Correction Method ◽  
Resistance Coefficient ◽  
Container Ship ◽  
Total Resistance ◽  
Air Resistance ◽  
Study Results ◽  
Resistance Performance

This study investigated the resistance performance of ships, using the air resistance correction method. In general, air resistance is calculated using an empirical formula rather than a direct calculation, as the effect of air resistance on the total resistance of ships is relatively smaller than that of water. However, for ships with large superstructures, such as container ships, LNG (liquefied natural gas) carriers, and car-ferries, the wind-induced effects might influence the air resistance acting on the superstructure, as well as cause attitude (trim and sinkage) changes of the ship. Therefore, this study performed numerical simulations to compare the total resistance, trim, and sinkage of an 8000 TEU-class container, ship with and without superstructures. The numerical simulation conditions were verified by comparing them with the study results of the KCS (KRISO Container Ship) hull form. In addition, the differences in the above values between the two cases were compared using the coefficients calculated by the empirical formula to identify the effects on the air resistance coefficient.

The Effect of Added External Resistance on Regional Pulmonary Filling and Emptying Sequences

1971 ◽  
Vol 49 (5) ◽  
pp. 406-411 ◽  
Author(s):  
R. R. Martin ◽  
J. E. Wilson ◽  
W. R. D. Ross ◽  
N. R. Anthonisen
Keyword(s):  
Flow Rate ◽  
Normal Subjects ◽  
Low Flow ◽  
Maximum Speed ◽  
Respiratory Effort ◽  
External Resistance ◽  
Flow Rates ◽  
Alveolar Plateau ◽  
Minimal Resistance ◽  
Maximal Effort

Using the radioactive 133Xe technique, the effects of external resistances on the distribution of inspired gas and on the expiratory alveolar plateau were examined in four normal subjects. Subjects inhaled 133Xe boli one of three ways: slowly through minimum external resistance, with maximum speed through minimal resistance, and with maximal effort but at very low flow rates through a large external resistance. Also, always after a slow inspiration through low resistance, subjects expired in three different ways: slowly through minimal resistance, with maximum speed through minimal resistance, and finally with maximal effort through an external resistance which sharply limited flow rates. Both regional intrapulmonary 133Xe distribution and the shape of the alveolar plateau appeared to depend entirely on flow rate and to be independent of effort. These results were interpreted as indicating that variations in respiratory effort do not produce variations in dynamic pleural pressure between lung regions.

scholarly journals PENGARUH MODIFIKASI BURITAN SPEED BOAT TERUBUK EXPRESS 6 TERHADAP KECEPATAN KAPAL

2018 ◽  
Vol 8 (2) ◽  
pp. 297 ◽  
Author(s):  
Edy Haryanto
Keyword(s):  
Diesel Fuel ◽  
Input Data ◽  
Field Survey ◽  
B Value ◽  
Maximum Speed ◽  
Total Resistance ◽  
Sea Transportation ◽  
Before And After ◽  
Shape Changes ◽  
Boat Speed

Speedboat Terubuk Express is a fast ship that is used as a means of sea transportation to carry passengers with a capacity of 60 people. Because it continues to experience losses, currently the Terubuk Express speedboat is modified by adding capacity and replacing the main drive engine which previously used an outboard engine with 4 x 200 horse power replaced with an internal engine that uses diesel fuel with power 1140 kilowatt. This study aims to determine the effect of stern shape changes and interaction total resistance before and after being modified on the hull to the speed of the ship.In this study several stages were carried out, namely a field survey to obtain the effect of size addition, making a model using Maxsurf 13.0 software, input data and running simulations using Hullspeed 13.01 then analyzing the results which included obstacles and speed.Based on the results of the analysis and calculations showed that the change in stern shape on the express speed boat speed caused L / B to increase by 1.2%, an increase in the comparison of the L / B value could affect the ability of the boat's motion and stability. The total resistance of the ship increased by 1.05% which at a speed of 35 knots before the change in total resistance was 33.5 kN while after the change in the total resistance became 35, 1 kN. Changes to the installed power engine can give a maximum speed of 49 knots with a total barrier of 47.5 kN. Increased speed greatly affects the engine seat and the strength of construction and the location of the longitudinal of bouyancy.

scholarly journals The equation of motion of a runner, exerting a maximal effort

1928 ◽  
Vol 103 (724) ◽  
pp. 218-225 ◽  
Keyword(s):  
Maximum Velocity ◽  
Frictional Resistance ◽  
Equation Of Motion ◽  
Internal Resistance ◽  
Maximum Speed ◽  
Mathematical Equation ◽  
External Resistance ◽  
Two Factors ◽  
Calculated Effect ◽  
Maximal Effort

Furusawa, Hill and Parkinson (1) have shown that the acceleration of a runner and the maximum speed he can obtain depend upon two factors, ( a ) the maximum force he can exert in propelling himself, and ( b ) the frictional resistance of his muscles. They have experiment these factors in a mathematical equation, which they have tested by experiment. The experimental results fit the equation very satisfactory and allow the values of the constants to be determined. The maximum velocity attained depends upon a balance between the propelling force, which is constant up to the onset of fatigue, and the internal resistance, which increases as the speed rises until it balances the propelling force. In spite of the accuracy with which experiment has been found to verify the equation, this internal resistance has to some degree a hypothetical existence. The object of the present paper is to give it greater reality by showing how an actual external resistance can be added on to it and produces exactly the calculated effect.

Detection of viruses by electron microscopy: Increased sensitivity by direct micro-ultracentrifugation of samples

1987 ◽  
Vol 45 ◽  
pp. 908-909
Author(s):  
Alain R. Trudel ◽  
M. Trudel
Keyword(s):  
Electron Microscopy ◽  
Fold Increase ◽  
Observation Time ◽  
Clinical Samples ◽  
Maximum Speed ◽  
Viral Particles ◽  
Structural Details ◽  
Latex Spheres ◽  
Increased Sensitivity ◽  
Size Of Particles

AirfugeR (Beckman) direct ultracentrifugation of viral samples on electron microscopy grids offers a rapid way to concentrate viral particles or subunits and facilitate their detection and study. Using the A-100 fixed angle rotor (30°) with a K factor of 19 at maximum speed (95 000 rpm), samples up to 240 μl can be prepared for electron microscopy observation in a few minutes: observation time is decreased and structural details are highlighted. Using latex spheres to calculate the increase in sensitivity compared to the inverted drop procedure, we obtained a 10 to 40 fold increase in sensitivity depending on the size of particles. This technique also permits quantification of viral particles in samples if an aliquot is mixed with latex spheres of known concentration.Direct ultracentrifugation for electron microscopy can be performed on laboratory samples such as gradient or column fractions, infected cell supernatant, or on clinical samples such as urine, tears, cephalo-rachidian liquid, etc..

Rapid Freezing of Freeze-Etch Specimens

1980 ◽  
Vol 38 ◽  
pp. 752-755
Author(s):  
A. Elgsaeter ◽  
T. Espevik ◽  
G. Kopstad
Keyword(s):  
Low Temperature ◽  
Metal Surface ◽  
Relative Velocity ◽  
Thermal Contact ◽  
High Rate ◽  
Rapid Freezing ◽  
Temperature Decrease ◽  
Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

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