• ### Is a hot object heavier than the cold one?

23 answers · 2 weeks ago
• ### According to gravity, why won’t electrons drop into the atomic nucleus inside an atom?

Best answer: This is similar to the earth orbiting the sun. In both situations the centripetal force is equal to the net force. I will use earth and the sun. Fc = m * v^2 ÷ r Fg = G * M * m ÷ r^2 m * v^2 ÷ r = G * M * m ÷ r^2 v^2 = G * M ÷ r v = √G * M ÷ r The mass of the sun is 1.991 * 10^30 kg. The distance from the earth... show more
Best answer: This is similar to the earth orbiting the sun. In both situations the centripetal force is equal to the net force. I will use earth and the sun.

Fc = m * v^2 ÷ r
Fg = G * M * m ÷ r^2
m * v^2 ÷ r = G * M * m ÷ r^2
v^2 = G * M ÷ r

v = √G * M ÷ r

The mass of the sun is 1.991 * 10^30 kg. The distance from the earth to the sun is 1.496 * 10^11 meters.

v = √(6.67 * 10^-11 * 1.991 * 10^30 ÷ 1.496 * 10^11
v = √(1.327997 * 10^20 ÷ 1.496 * 10^11) = 29,793.672 m/s

The circumference of the circle is 2 * π * 1.496 * 10^11

To determine the time for the earth to orbit the sun, divide the circumference by the velocity

t = 2 * π * 1.496 * 10^11 ÷ 29,793.672
This is approximately 3.15 second

One year * 365 days/year * 24 hr/day * 60 min/hr * 60 s/min = 3.1536 * 10^7 seconds
Since these times are approximately equal to each other, this proves that the time is correct. If you did the same math for the electron and the nucleus, you would find the velocity of the electron.
15 answers · 2 weeks ago
• ### I have a space station creating artificial gravity via linear acceleration. how would you use momentum to find the stations fuel consumption?

Best answer: To maintain 1G of gravity, you have to accelerate at that rate. if the mass of the craft is m, then you need to apply a force F = ma where a = 10 m/s² if you continue that for t seconds, d = ½at² d = ½10•t² = 5t² meters traveled work = energy needed = Fd = ma(5t²) = 10m(5t²) = 50mt² that tells you the energy... show more
Best answer: To maintain 1G of gravity, you have to accelerate at that rate.

if the mass of the craft is m, then you need to apply a force F = ma where a = 10 m/s²

if you continue that for t seconds, d = ½at²
d = ½10•t² = 5t² meters traveled

work = energy needed = Fd = ma(5t²) = 10m(5t²) = 50mt²
that tells you the energy needed.
velocity = at = 10t
momentum = mV = 10mt

If you are just throwing reaction mass out the back at velocity V₀, then the momentum of the fuel thrown out the back is m₀V₀
m₀V₀ = 10mt
so the mass of fuel used is
m₀ = 10mt/V₀

To try some numbers....
if you have a craft mass of 10000 kg, a time of 3600 seconds (1 hour), fuel velocity of 1e8 m/s (1/3 of light, pretty extreme)
then mass of fuel would be
m₀ = 10mt/V₀ = 10•10000•3600/1e8 = 3.6 kg
this is for every hour.

at some point, the mass thrown away would become a significant portion of the total mass, and the equations would change.

or course you would reach relativistic speeds at some point so the equations would change. v = at.
to reach c/2, t = 1.5e8/10 = 1.5e7 seconds or about 6 months.
6 answers · 2 weeks ago
• ### A car traveling 34 mi/h accelerates uniformly for 6.3 s, covering 557 ft in this time. What was its acceleration? Answer in ft/s .?

8 answers · 2 weeks ago
• ### I've been given 'power' for homework after olms law. How much about power should I get to learn for homework?

Hi, I am attending college and doing electrical installation level 1. We have just done olms law which was very very easy. He just drew an empty triangle on the board with 'power' next to it. Then said take a photo of that and then use google to do it at home basically. Surely he must be expecting us to... show more
Hi, I am attending college and doing electrical installation level 1. We have just done olms law which was very very easy. He just drew an empty triangle on the board with 'power' next to it. Then said take a photo of that and then use google to do it at home basically. Surely he must be expecting us to do more homework than just learn to multiply voltage by current though lol.
10 answers · 2 weeks ago
• ### Question on Motion?

Best answer: The ball was initially in the hand and finally in the hand.
since displacement is the distance moved from its initial position, the displacement is zero.
Best answer: The ball was initially in the hand and finally in the hand.
since displacement is the distance moved from its initial position, the displacement is zero.
9 answers · 2 weeks ago
• ### Is there a way to determine when an object s temperature is falling most rapidly according to Newton s Law of Cooling?

10 answers · 2 weeks ago
• ### If light has no mass, how does it have energy?

13 answers · 2 weeks ago
• ### An airplane starts from rest and reaches a takeoff velocity of 60.0 m/s due north in 4.0 s. How far has it traveled before takeoff?

7 answers · 2 weeks ago
• ### A metal cube 8cm^3 has a density of 6600 kg/m^3 find its mass when it is totally submerged in water?

6 answers · 2 weeks ago
• ### Will the explosion of nuclear weapons produce gamma rays?

Best answer: Absolutely. The entire spectrum of electromagnetic waves are produced within the explosion.
Heat, light, x rays, gamma rays.
This is the short term cause of damage.
Arriving well before any blast. The heating and subsequent expansion through absorbing all of this energy ultimately causes the blast somewhat later.
Best answer: Absolutely. The entire spectrum of electromagnetic waves are produced within the explosion.
Heat, light, x rays, gamma rays.
This is the short term cause of damage.
Arriving well before any blast. The heating and subsequent expansion through absorbing all of this energy ultimately causes the blast somewhat later.
5 answers · 2 weeks ago
• ### Does current depend upon area of cross section?

I=V/R and R is inversely proportional to area of crosssection so if area of cross section increases then R must decrease and current must increase keeping V constant But my book says that for a conductor current is constant
I=V/R and R is inversely proportional to area of crosssection so if area of cross section increases then R must decrease and current must increase keeping V constant But my book says that for a conductor current is constant
10 answers · 3 weeks ago
• ### On what basis did Einstein in his 2nd postulate of Special relativity determine that the speed of light has no relativity to its source?

Best answer: He did not determine this from observation or experiment. He merely hypothesized that the speed of light was constant for all observers and worked out the consequences. The consequences explained many observed phenomenae and have continued to be useful and accurate in explained new observations as they are made.... show more
Best answer: He did not determine this from observation or experiment. He merely hypothesized that the speed of light was constant for all observers and worked out the consequences. The consequences explained many observed phenomenae and have continued to be useful and accurate in explained new observations as they are made. When others take these results and use them in further predictions, those results also agree with observed reality. Therefore, we accept the initial assumption as very likely to agree with the way the world works, even though initially it seemed contrary to intuition. That's how science works.
5 answers · 2 weeks ago
• ### How large of a pot of water could you boil?

Hard question to word. Like could you boil a huge pot of water the size of a house? Is there a limit to how big you could do it? If you could I d imagine it d be pretty dangerous :p
Hard question to word. Like could you boil a huge pot of water the size of a house? Is there a limit to how big you could do it? If you could I d imagine it d be pretty dangerous :p
10 answers · 2 weeks ago
• ### On a shopping trip, marge drove 3 km at 60 km/h, 5 km at 120km/h, and 3 km at 40 km/h. Her average speed for the whole trip was?

9 answers · 2 weeks ago
• ### Is there anything in existence that we cannot see, hear, smell or touch?

38 answers · 3 weeks ago
• ### A running mountain lion can make a leap 10.0 m long, reaching a maximum height of 3.0 m.?

Best answer: When the lion is at the maximum height, its vertical velocity is 0 m/s. Let’s use the following equation to determine the initial vertical velocity. vf^2 = vi^2 + 2 * g * d 0 = vi^2 + 2 * -9.8 * 3 vi = √58.8 This is approximately 7.7 m/s. This happens during one half of the total time. Let’s use the following... show more
Best answer: When the lion is at the maximum height, its vertical velocity is 0 m/s. Let’s use the following equation to determine the initial vertical velocity.

vf^2 = vi^2 + 2 * g * d
0 = vi^2 + 2 * -9.8 * 3
vi = √58.8

This is approximately 7.7 m/s. This happens during one half of the total time. Let’s use the following equation to determine this time.

vf = vi – g * t
0 = √58.8 – 9.8 * t
t = √58.8 ÷ 9.8

This is approximately 0.78 seconds. The total time is twice this time. During the total time, the lion moves a horizontal distance of 10 meters. Let’s use the following equation to determine the horizontal component of the lion’s initial velocity.

d = v * t
10 = v * 2 * √58.8÷ 9.8

v = 49 ÷ √58.8

This is approximately 6.4 m/s.

Speed = √[58.8 + (49 ÷ √58.8)^2]

This is approximately 10 m/s. To determine the angle from horizontal, use the following equation.

Tan θ = Vertical ÷ Horizontal
Tan θ = √58.8 ÷ (49 ÷ √58.8) = 1.2
The angle is approximately 50˚. I hope this is helpful for you.
7 answers · 2 weeks ago
• ### Does sound exist if no one hears it ?

I had a lengthy discussion with a friend. I told him sound exists even if we do not hear it. He said sound can only exist if we can sense it. Who is correct ?
I had a lengthy discussion with a friend. I told him sound exists even if we do not hear it. He said sound can only exist if we can sense it. Who is correct ?
14 answers · 2 weeks ago
• ### Compare from greatest to least the accelerations of these skydivers?

Best answer: g is approximated to 10 m/sec^2 a) 1000-N man with 800N of air drag mass m = 1000/10 = 100 kg acceleration a = (weight-drag)/mass = (1000-800)/100 = 2.0 m/sec^2 b) 800-N woman with 700N OF air drag mass m = 800/10 = 80 kg acceleration a = (weight-drag)/mass = (800-700)/80 = 1.25 m/sec^2 c)700-N woman with 600N... show more
Best answer: g is approximated to 10 m/sec^2

a) 1000-N man with 800N of air drag
mass m = 1000/10 = 100 kg
acceleration a = (weight-drag)/mass = (1000-800)/100 = 2.0 m/sec^2

b) 800-N woman with 700N OF air drag
mass m = 800/10 = 80 kg
acceleration a = (weight-drag)/mass = (800-700)/80 = 1.25 m/sec^2

c)700-N woman with 600N of air drag
mass m = 700/10 = 70 kg
acceleration a = (weight-drag)/mass = (700-600)/70 = 1.43 m/sec^2

d) 100-N dog with 90 N of air drag
mass m = 100/10 = 10 kg
acceleration a = (weight-drag)/mass = (100-90)/10 = 1.00 m/sec^2

then a) ; c) ; b) ; d)
4 answers · 2 weeks ago
• ### Has the equation E= MC^2 been incomplete since mass is not equal to energy & Energy consist of multiple fields?

Best answer: No the equation is NOT incomplete. Mass and energy ARE interchangeable, BUT the process is inefficient because of entropy. Energy also equals the Plank constant times frequency with NO term for MASS at all. THAT equation is also NOT incomplete. The speed of light IS NOT CONSTANT. This is a FALSE assumption... show more
Best answer: No the equation is NOT incomplete.

Mass and energy ARE interchangeable, BUT the process is inefficient because of entropy. Energy also equals the Plank constant times frequency with NO term for MASS at all. THAT equation is also NOT incomplete.

The speed of light IS NOT CONSTANT. This is a FALSE assumption because your facts are uncoordinated and your thinking becomes illogical and incomplete. Light is BOTH an electric AND a magnetic field. Light is BOTH a wa ebAND particles, photons.
6 answers · 2 weeks ago