scilearner

Thank you insane alien The water is smooth compared to the irregular texture of the floor, so there less friction.

If you come in contact with any object, it is not going to resist your movement right, why doesn't ice do this much. What chemical property is responsible for this?When I slide in ice, am I coming into less contact with ice, I don't understand. Thanks

Thanks for all the answers Wait I didn't know this before. So car exerts force on road, road exerts on tyres, that's how the car moves forward. So how does a car move in ice, if the road is not exerting a force on the tyres? So can you easily brake on ice because friction between the wheel bearings can be achieved. Can you elaborate on this. Upto this point I was thinking car moving forward, friction from the road stopping the car? Why is this wrong?

Hello everyone, I have got confused with this. Normal the friction force acts to cancel the force. If I travel with 10 N force and friction is 5N, I travel at 5N. Why is that when you make a turn they don't create a net force, but act as separate forces? EDIT: I suppose the tires are turning outward all the time in different directions to keep it on the road. when you have turn in the circle outward force is little bit greater than friction I think, which makes the car turn in the right direction, before it is stopped by friction again.

Thanks skeptic So if there is a cancer of stomach cells, if they spread to lung, do stomach cells replicate there or lung cells replicate there. How do cancer cells flow through lymphatic system. Aren't they too big?

Hello everyone, First of all I don't know much about cancer. I'm assuming cancer is some mutation in dna and causes the cells to uncontrollably replicate. So let's say a person has lymphoma. Now this cancer spread into lungs? Then what happens? Do lung cells start to replicate there or lymphoid cells start to replicate there?If lung cells start to replicate, how does a lymphomatic cancerous cell spread the mutation to a lung cell? I mean it is not like a virus that can inject DNA right? Also how do cancers spread through lymphatic system? Lymphatic system can not carry cells right, only interstitial fluid so how does cancer spread through them? Thanks

Thanks again Is all fluid drained from lymphatic system or isn't it only some part of interstitial fluid that is drained from lymphatic system at one time. Or did you mean that eventually all fluid would be drained.

Thanks Grieppi So if they diffuse everywhere, when it comes to important area like throat in this case, could there be less antibiotical agents. I mean sometimes can they be wasted going to unnessecary areas or is the quantity always enough.

Hello everyone, Let's say I have a throat infection and all the bacteria are near the throat. I get antibiotics. So if these antibiotics enter bloodstream, how do they know they have to diffuse out right near the throat area. Are they diffusing all the time, going to unwanted places. Why is it bad to get antibiotics frequently, I can understand they will kill good bacteria, but how does this create antibiotic resistance to bad bacteria. Thanks

Thanks DoubleK. However I don't understand why neurons need to be continuously supplied with ATP. Is it because they need ATP to open protein channel to carry out action potential, or is the extra cellular matrix of a neurone determined by the blood supply. If a neurone can not carry out cellular respiration, why would it cause permanent damage to the structure? EDIT: Without ATP you want have the proper concentration of solutes inside the cell, so the cell can swell and burst. Is that what happens?

Thanks for all the answers They were all very helpful. Ok if the cell don't gain energy, can't that part of the brain shut down temporarily without dying, what I mean is can't the brain make you unconscious and cut down all your activity until someone fixes it. I think when I think of energy I only think of cellular respiration, if cellular respiration stops I can understand how all the metabolic activity would stop but why would structure of the cell break down. Thanks EDIT: Do you need ATP to sustain the phospholipid bilayer of cells?

Hello everyone, These might be stupid but I'll ask anyway. Ok let's say a person died because a major artery supplying the brain was damaged. After a while if someone fixes the artery and supply some blood, would the person come alive again. What basically I'm asking is if someone died to reversible damage like this, if you fix it soon can he come back alive. Ok why doe many people die due to brain damage, if they are still breathing and the heart is pumping aren't they still living?How can damage to the brain affect breathing or pumping of heart? So if you fix their brain damage would they come back alive. Also why is their no pulse after you die, if the heart is autopacemaker and is still beating. Thanks

Thanks Sisphysus. You answered the question very well. I think so whenever you compress something like a spring, it comes back to its orginal shape giving a force, and if you get hit by it, you can use its elastic energy to do work on the hit object.

Thanks for the reply swansont:-) So if there is a spring attached to the wall and I compress it and take my handaway. The spring recoils, now where is extra elastic potential converted to or given. Do the air molecules get the extra elastic potential energy. Or sometimes does the spring if not attached to a wall, jump up due to extra energy.

Now when the spring recoils, it loses its elastic potential energy to the dart. If it loses its energy how does it come back to its original shape. I'm thinking it is the elastic potential energy that is used to make the coil come back to its orginal shape. Also let's say a spring was compressed and I took my hand away. Now it recoiled back to its shape. The spring didn't transfer any of its added elastic potential energy, to any other object. So does the spring has more energy now. When I compress a spring I'm thinking I'm adding extra potential energy. Am I adding extra energy or, changing the allready existing energy in the spring to elastic potential energy. Please excuse anyof my misunderstandings. Thank you

Hey thanks both for the replies So is the tension coming from both the tripod and the elasticity of the string? If tension is coming from the tripod, how is the tripod able to provide tension. I don't understand what causes tension. Can anyone explain in physics or molecular level what causes the tension.Now my question is simply what is the reason behind tension force. I know air resistance is caused by air but what causes tension? Also if I hang a mass to a string, and then it stretches a bit and then forces balance remains stationary. I hang a bigger mass and it stretches further and forces balance remain stationary. Why did it stretch further in the 2 nd situation for the forces to balance. Thanks

Hello everyone, Let's say there is a tripod. I attach a string to the tripod and then attach a mass to the string. The string with the mass ,stretches a bit and then the mass hangs in the air. So this means the weight force of the mass must be balanced by the tension of the string. Now let's say this tension is coming from the elasticity of the string. Now after the mass is hung, I take it off and look at the string, now it is stretched and loss its elasticty. So if I attach this string to the tripod again, and hang the mass, and it stretches a bit and stays stationary, where is the tension of the string coming from. It can't come from the string because it has lost its elasticity.

Hey that is a very interesting piece of information. Thanks for that However I mean there is no full proven explanation for this yet right?

Hello everyone, If an object is hanging from a string in the wall. It is stationary so this means tension of the string and weight force of the object must be equal. Is this tension coming from the elasticity of the string. So if the string loses its elasticty by a heavy force, does that mean there would no be a tension foce and the object would keep going down and fall to the ground. When the spring is elastic it stores its energy as elastic potential energy, when it becomes plastic like, is this energy converted to change the structure of the object.

Hey thanks a lot for the reply J.C.MacSwell That makes me think Newton's third law can be also derived from balancing centre of mass in situations like this. Like a seesaw. I have never thought about it that way. Thanks

Oh are you saying energy is W=fx. So bullet travels further and has more energy but the energy from the explosion gives the same force to both. EDIT: But I still don't understand. Why does gun powder give a forward force to the bullet and backward force to the gun. Also why is this question not about gun powder and bullet. If gun powder provides the force, the reaction force should be towards gun powder, not the gun. EDIT AGAIN: Let me think this again. If force is rate of change of momentum. Since gun powder is part of the gun, the gun changed the momentum of the bullet. Oh so you can't change the momentum of something else without that momentum coming from you, meaning losing it. Oh so the gun retaliates. Oh so basically if you want to displace something, the person who is trying to displace the object is going to get displaced as well atleast a tiny bit. May be that is what momentum is saying. Is this right?

Thanks swansont Now we atleast know my misunderstanding, but I'm still bit uncertain. How does the gun powder divide the energy equally between the gun and the bullet, how come bullet doesn't get excess energy or something. Also I'm thinking gun powder applies a force at the bullet, so bullet must apply a force at the gun powder not the gun. My other misconception is I don't understand much the difference between momentum and kinetic energy. I know one is a scalar quantity but let's say there was a momentum collision and the 2 objects united and went off together after that. Then the kinetic energy is not conserved but momentum is I don't understand why? Thanks for any help in advance

Ok thanks then I have a final question. If a gun and bullet were at rest. Then when the bullet was fired gun recoiled. The energy for this came from gun powder. The gun powder provides energy only for the bullet so why does the gun recoil back. Gun hasn't lost any energy. Thanks

Ok forgetting all this. Swansont I basically want to know why Newton's third law occurs. If I push a box that was at rest. The box started to move. Then if I work out the change of momentum I realize 2 opposing forces have acted. Is this the explanation for Newton's third law?

Hey thanks swansont. Why is in either case momentum is zero. -1 -1=-2. Let's say if a ball was coming towards you and you hit it a with a bat, then the ball flies in opposite directions. If the balll came at you at 1 m/s (direction towards you) and went away from you at -1m/s why is change of kinetic energy zero. Could you show me from examples or otherway. Thanks