The electromagnetic force between two charged particles is much greater than the strength of gravity between them, no matter how far apart they are
Nevertheless, it is gravity, rather than the electromagnetic force, that dominates the universe on large scales. Briefly explain why.
Despite its far greater strength per particle, the electromagnetic force is unable to attain very large values because it is impossible to accumulate a very large charge. This is because large objects tend to have equal amounts of positive (protons) and negative (electrons) charge, and the electromagnetic force thus "cancels" itself out. Gravity, on the other hand, always attracts: As objects get more and more massive, gravity continues to gain strength. Thus, for very large objects, there will be a great deal of gravitational attraction but virtually no electromagnetic force, since the overall object is neutral.
You might also like to view...
Which two classes of objects were critical to the Shapley-Curtiss Debate of 1920?
A) white dwarfs and red giants B) open clusters and emission nebulae C) globular clusters and spiral nebulae D) emission nebulae and spiral nebulae E) planetary nebulae and white dwarfs
Which of the following conditions makes stars appear dim?
A) The scattering of light by the dust in clouds B) The luminosity of the neighboring star C) The increasing mass of all the stars D) The gravitational force from the planets
Derive an equation in the form ch = f(T, D, U?) for flow of air over a long horizontal cylinder for the temperature range 0°C to 100°C, as a basis for water in the temperature range 10°C to 40°C.
GIVEN
• Water flow over a long horizontal cylinder
• Water temperature range is 10°C < T < 40°C
FIND
• An equation in the form h c= f(T, D, U?) based
ASSUMPTIONS
• Steady state
• Temperature difference between water and the cylinder is small enough that the Prandtl number variation is negligible
• The density of water can be considered constant
SKETCH
A substance is heated from 23°C to 45°C. What would the same incremental change be when registered in kelvins?
a. 22 b. 71.6 c. 295 d. 34 e. 28