• ### Is time travel possible?

Do you think we will ever be able to do this?
Do you think we will ever be able to do this?
18 answers · 3 days ago
• ### If you shoot a bullet into the air, does it come back down?

Best answer: Yes; of course and people do get killed from this sometimes. That's why it's not smart to shoot off guns in the air like you see sometimes in movies and television or sometimes will see at wedding celebrations in some of your countries in SWA.
Best answer: Yes; of course and people do get killed from this sometimes. That's why it's not smart to shoot off guns in the air like you see sometimes in movies and television or sometimes will see at wedding celebrations in some of your countries in SWA.
18 answers · 3 days ago
• ### Why do aeroplanes have a green light on one wing and a red light on the other?

6 answers · 5 hours ago
• ### Need help with physics/energy problem. Much Appreciated!!?

Levers are a clever way of moving something heavy that you wouldn’t be able to move just by pushing on it. A lever consists of a “lever arm”, which is free to pivot about a point, or “fulcrum”. It relies on having the distance L1 be larger than L2. By pushing on the long arm, the force F1 you apply gets... show more
Levers are a clever way of moving something heavy that you wouldn’t be able to move just by pushing on it. A lever consists of a “lever arm”, which is free to pivot about a point, or “fulcrum”. It relies on having the distance L1 be larger than L2. By pushing on the long arm, the force F1 you apply gets multiplied, and a much larger force F2 is applied to the load. At first glance, it seems like you get “something for nothing” when using a lever; you apply a small force, and you’re able to move an object with a much larger force! On closer inspection, it turns out not to be so; the work done on the object matches exactly the work you put in. Here, we will derive the basic lever equation F1/F2 = L2/L1 Part 1 If you push the long end of the lever down a distance d1, how much does the other end move up? (Call this distance d2.) Express you answer in terms of L1 and L2. Part 2 Assume that the work you do is equal the work done on the load. Express this assumption in terms of the forces F1 and F2 and displacements d1 and d2, and use your answer from part 1 to derive the lever equation. Part 3 (you can do this part without doing part 1 or 2) If I gave you a lever arm 10 m long, where would you have to rest it on the fulcrum to lift a 1000 kg object off the ground? (I.e., what must the ratio L1/L2 be?) (Hint: The force you can exert is probably largest if you lean on it and push down with all your weight.)
7 answers · 3 days ago
• ### Professor Stephen Hawking has passed away at the age of 76?

Best answer: When I was 5 my mom read me George’s Secret Key to the Universe, that book shaped my earliest years, making me obsessed with being as smart as Stephen Hawking. Thank you Mr. Hawking, and I’m so sorry Lucy Hawking for your loss.
Best answer: When I was 5 my mom read me George’s Secret Key to the Universe, that book shaped my earliest years, making me obsessed with being as smart as Stephen Hawking. Thank you Mr. Hawking, and I’m so sorry Lucy Hawking for your loss.
7 answers · 2 days ago
• ### Physics class is killing me :(?

An owl is carrying a mouse to the chicks in its nest. It is 4.00 m west and 12.0 m above the center of the 30 cm diameter nest and is flying east at 2.50 m/s at an angle 32° below the horizontal when it accidentally drops the mouse. Will it fall into the nest? Find out by solving for the horizontal position of the... show more
An owl is carrying a mouse to the chicks in its nest. It is 4.00 m west and 12.0 m above the center of the 30 cm diameter nest and is flying east at 2.50 m/s at an angle 32° below the horizontal when it accidentally drops the mouse. Will it fall into the nest? Find out by solving for the horizontal position of the mouse (measured from the point of release) when it has fallen the 12.0 m.
9 answers · 3 days ago
• ### The pressure exerted by the weight of earths atmosphere?

6 answers · 2 days ago
• ### How are things waves?

Best answer: Classically, light is a combined wave in an electric field and a magnetic field where essentially the motion in each field causes motion in the other. it is a sort of self perpetuating pair of waves that can travel indefinitely in a vacuum until they encounter matter. The whole wave / particle quantum business is... show more
Best answer: Classically, light is a combined wave in an electric field and a magnetic field where essentially the motion in each field causes motion in the other. it is a sort of self perpetuating pair of waves that can travel indefinitely in a vacuum until they encounter matter.

The whole wave / particle quantum business is a different more fundamental model of light from which the classical view emerges at larger scales. It is pointless to try and explain quantum theory in a few lines but the wave part more or less describes the probability of where a particle could be and the particle part is that ultimately a particle of light will turn up in random a location determined by the probability wave. The medium for the probability wave of light seems to be just space itself (or spacetime).
5 answers · 3 days ago
• ### Does filling a room with water vapor increase the air pressure in the room?

Best answer: The partial pressure of one gas adds to that of the other. So the pressure would increase if all other factors were kept constant. Now the act of evaporating the water LOWERS the temperature so unless HEAT was added through the walls the air would tend to shrink. But if it remained at the same temperature and it... show more
Best answer: The partial pressure of one gas adds to that of the other. So the pressure would increase if all other factors were kept constant.
Now the act of evaporating the water LOWERS the temperature so unless HEAT was added through the walls the air would tend to shrink.
But if it remained at the same temperature and it was sealed then the pressure increases by the partial pressure of water at that temperature.

I should add that this is how clothes dry on the clothesline. The evaporating water increases the local pressure slightly so the moist air moves outwards from the clothes. The water diffuses outwards even in the absence of any wind or other air current.

For example at boiling point the partial pressure of water is 1 atmosphere. It is capable of pushing the atmosphere out of the way. That is what boiling means.
So if your container had both air and water the pressure could rise substantially higher than if the container had ONLY water vapour in it.

PS the reverse is true. If you boil the water and exclude the air, then seal the container and let it cool, the pressure drops to ONLY the partial pressure of the water.
This is much less than atmospheric. So a weak container crushes.

A stronger container keeps the water at "boiling point" at all times.
The slightest heat on the water makes it immediately boil.
Put a glass container like this in your hand and watch the water boil at skin temperature.

Fun
6 answers · 4 days ago
• ### Explain to a dummy "photons have mass and at rest that mass is zero". That whole bit about mass converting to energy, but not the opposite?

5 answers · 2 days ago
• ### Why doesn't a plane traveling against the rotation of the earth arrive at its destination faster than if it were to rotate with it?

I need a simple explanation please!
I need a simple explanation please!
8 answers · 3 days ago
• ### List any 5 examples of inertia from daily life?

8 answers · 6 days ago

He clearly trusts Putin. Why not just ask?
He clearly trusts Putin. Why not just ask?
4 answers · 3 days ago
• ### Did Albert Einstein ever drink a coke during his life?

Best answer: i see that i'm no einstein, but drinking cokes does not cause diabetes or obesity, not even in those with hereditary genetic dispositions.

check biological sciences.
Best answer: i see that i'm no einstein, but drinking cokes does not cause diabetes or obesity, not even in those with hereditary genetic dispositions.

check biological sciences.
5 answers · 4 days ago
• ### Is the future going to occur no matter what?

Best answer: Yeah, that's kind of how time works
Best answer: Yeah, that's kind of how time works
6 answers · 4 days ago
• ### What would happen, if the velocity would be higher, than orbital velocity?

Best answer: As long as the velocity is less than escape velocity then the initial direction of motion depends on the direction of the added velocity. However the total kinetic energy has increased. So at some point the object will get further from the central body. At this point the gravitational potential has... show more
Best answer: As long as the velocity is less than escape velocity then the initial direction of motion depends on the direction of the added velocity.
However the total kinetic energy has increased.
So at some point the object will get further from the central body.
At this point the gravitational potential has "absorbed" the extra kinetic.
Now the gravitational force is greater than the required centripetal force and the body falls toward the planet.
But this increases the speed. So half a cycle later the body is at its closest point.
It has a high kinetic energy and a high speed so that the required centripetal force is greater than the gravitational force.

The body once more goes outward.

This is actually what all real orbits are. They are an ellipse. Where at the distance R they have too much kinetic energy to have a circular orbit.
So they orbit between a minimum of r1 to a maximum of r2.

You can consider it in two ways. One way is that you have added SHM on top of the circle.
The better way is to realize that SHM and circular motion are both special cases of the general motion which is an ellipse.
( shm is an ellipse with a width of zero and a circle is an ellipse with both axes equal. )
5 answers · 3 days ago
• ### Simple physics question? f=ma?

ok this isn't for homework or anything, just curiousity so force = mass * acceleration but imagine that a car is going with the velocity of 60 mph (with no acceleration), meaning force = mass*0=0 why is it that if the car hits a wall, it exerts some type of force to damage the wall? what am i missing? thanks
ok this isn't for homework or anything, just curiousity so force = mass * acceleration but imagine that a car is going with the velocity of 60 mph (with no acceleration), meaning force = mass*0=0 why is it that if the car hits a wall, it exerts some type of force to damage the wall? what am i missing? thanks
5 answers · 3 days ago
• ### Is it certain that matter is non-deterministic on a quantum scale?

Does the present understanding of quantum mechanics conclusively demonstrate that subatomic particles actually behave probabilistically? Or could it be the case that their behavior is as deterministic as billiard balls, but much more exotic, and at present the best math we have to describe them is probabilistic? It... show more
Does the present understanding of quantum mechanics conclusively demonstrate that subatomic particles actually behave probabilistically? Or could it be the case that their behavior is as deterministic as billiard balls, but much more exotic, and at present the best math we have to describe them is probabilistic? It is my understanding that classical mechanics is deterministic, I can understand that on a smaller scale things might be quite different, but I don't get how non-determined particles could give rise to fully determined objects. Do we have good reason to believe that the present models of quantum behavior are accurate and not merely useful? Obviously the men and women who came up with the models had incredible minds, and achieved similarly incredible things, this is in no way an attempt to call in to question their competence or worth. And I know next to nothing about physics, my apologies if this is a stupid question.
5 answers · 4 days ago
• ### Explain simple pendulum?

4 answers · 4 days ago