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amm1812
3 years ago
14

The force exerted by expanding gases is what propels a shell out of a gun barrel. Suppose a force that has an average magnitude

F propels the shell so that it has a speed v at the instant it reaches the end of the barrel.
A) What magnitude force is required to double the speed of the shell in the same gun?
Physics
1 answer:
masya89 [10]3 years ago
8 0

Answer: 2F

Explanation:

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Help with these questions
erma4kov [3.2K]
<h2>Explanation:</h2><h3>3. </h3>

When light bounces back, it is <em>reflected</em>. (That's why you see your <em>reflection</em> in a mirror.) When light is bent from the path it is taking, it is <em>refracted</em>. The only answer choice that makes correct use of these terms is the third choice:

  • Part of the ray is <em>refracted</em> into ray B; part of the ray is <em>reflected</em> as ray R.

_____

<h3>4.</h3>

The index of refraction is the ratio of the sine of the angle of incidence to the sine of the angle of refraction. Both angles are measured from the normal to the surface. The angle of refraction here is 12.5° less than the angle of incidence, 44°, so is 31.5°. Then the index of refraction of the medium is ...

  n = sin(44°)/sin(31.5°) = 0.69466/0.52250 = 1.3299 ≈ 1.33

  • none of the offered choices is correct. The closest is 1.34.
8 0
3 years ago
LO NECESITO PARA HOY URGENTE!! 2. Exprese en metros las siguientes longitudes a) 48,9 km b) 36,875 cm c) 756,34 hm d) 9876 mm
Vesnalui [34]

Answer:

a)48900 metros

b)0.36875 metros

c)75634 metros

d)9.876 metros

Explanation:

Hola, para resolver debemos convertir unidades utilizando equivalencias

a) 48.9 km  

1 kilometro = 1000 metros

48.9 x 1000 = 48900 metros

b) 36.875 cm  

1 centímetro =0.01 metros

36.875 x 0.01 = 0.36875 metros

c) 756,34 hm

1 hectómetro= 100 metros

756.34 x 100 = 75634 metros

d) 9876 mm

1 milímetro = 0.001 m

9876 x 0.001 = 9.876 metros

4 0
3 years ago
Diagram B D c с Which car has: Ke = 100 PE=0? * 1 point A B C D​
erma4kov [3.2K]

Answer:

The car C has KE = 100, PE = 0

Explanation:

The principle of conservation of energy states that although energy can be transformed from one form to another, the total energy of the given system remains unchanged.

The energy that a body possesses due to its motion or position is known as mechanical energy. There are two kinds of mechanical energy: kinetic energy, KE and potential energy, PE.

Kinetic energy is the energy that a body possesses due to its motion.

Potential energy is the energy a body possesses due to its position.

From the principle of conservation of energy, kinetic energy can be transformed into potential energy and vice versa, but in all cases the energy is conserved or constant.

In the diagram above, the cars at various positions of rest or motion are transforming the various forms of mechanical energy, but the total energy is conserved at every point. At the point A, energy is all potential, at B, it is partly potential partly kinetic energy, However, at the point C, all the potential energy has been converted to kinetic energy. At D, some of the kinetic energy has been converted to potential energy as the car climbs up the hill.

Therefore, the car C has KE = 100, PE = 0

6 0
3 years ago
Most of the resistance of the human body comes from the skin, as the interior of the body contains aqueous solutions that are go
ruslelena [56]

Answer:

a) Resistivity=R.A/L

Here, R=500000ohm, L=1.6m, A=2pi* (0.14/2)*0.002 m2=0.00088.........we have converted quantities into SI units

Resistivity=R.A/L

=500000*0.00088/1.6 = 440/1.6= 275 ohm.meter

b) pskin/pinterior =275/4.8=57.3

For second part, correct option is (A), because cross section area is smaller.

4 0
3 years ago
What pushes against gravity in: a main sequence star, a white dwarf, a neutron star, and a black hole? electron degeneracy, neut
Inga [223]

Answer:

heat pressure, electron degeneracy, neutron degeneracy, and nothing

Explanation:

Main Sequence Star: It is a star in which nuclear fusion is happening in the core of the star. Hydrogen molecules fuse together to generate Helium. This nuclear fusion generates outward gas pressure and radiation pressure which balances the inward gravity thus creating an equilibrium which keeps the stars in shape.

White dwarf: It is the end stage of a medium sized star like the Sun. Outer layers of the star are thrown in the form a shell/bubble leaving a small and dense core in the center called as white dwarf. This core consists of carbon and oxygen. Nuclear fusion doesn't occur in the core of white dwarfs. The inward gravity is balanced by the electron degeneracy pressure. Thus these stars will keep on radiating the remaining heat and will turn in to a black dwarf at the end.

Neutron Star: This is the end stage of a supermassive star (1-3 times the mass of the Sun). At the last stage of the life the core collapses. In these stars the inward gravity is so huge that the pressure overcomes the electron degeneracy pressure and crushes together the electron and proton to form neutron. The neutron then stops the collapse and balances the inward gravity.

Black Hole: This is the end stage of a hyper massive stars weighing more than 3 times the mass of the Sun. The inward gravitational force is so huge that even the neutrons are not able to stop the collapse the core. thus the mass of the star collapses into a very small area of immense gravity. There is nothing that can balance this inward gravity.

3 0
2 years ago
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