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In a rotating system such as a ball swung on a piece of string your hand exerts an inward radial centripetal force on the ball, this is the force that causes the ball to rotate. The ball, in its turn, exerts an outward radial force on your hand. Both forces are real. The ball is "Exerting" a centrifugal force, it is not subject to such a force. Release ...


1

It's a mistake to think of a body in orbit having its forces 'balanced' in some way - the forces are not balanced, because the body is accelerating towards the centre of the orbit! See my BBC article here, which explains this and weightlessness in general terms. I hope it helps. http://news.bbc.co.uk/1/hi/magazine/4625150.stm


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I just found your question because I was thinking the same, as I read the passage about 'Dragonfly.' As Dmckee said, there must be aerodynamic effects from the rotation (the air-bike wouldn't move otherwise), but it doesn't make sense that he'd feel .3g or whatever, since he's not in a gravity well. It would be more like scuba diving in a pool with a ...


0

You know that the centripetal force is given by $\vec F_z = m\omega^2r \, \vec e_r$ ,where $\vec e_r = \cos \theta \, \vec e_x + \sin \theta \, \vec e_y$ is the unit vector in radial direction. We want to calculate the work given by the line integral $$ \int_C \vec F_z \cdot \mathrm d \vec r $$ where the position of the point mass $\vec r = r\, \vec e_r$ ...


0

The use of a Tesla high vacuum pump is indeed very compelling. I did some research during university for its use as a fluid pump, quite similar to the 2008 one you cited. I guess the design approach might be that of the many particles. At ambient temperature, the average speed of air molecules is about 500 m/s, which is comparable to the tip speed of a high ...


1

I came up with a solution seeing John Rennie's comment. The centripetal force, $\vec F= -F \hat r $ so infinitesimal work done by centripetal force, $$dW=\vec F.d \vec r= -F \hat r.d\vec r$$ but, $\hat r⊥d \vec r$ so $$dW=0$$ is this correct ?


1

A spinning space station does not provide artificial gravity away from Earth, it provides artificial gravity toward the center of the station. The first effect the spinning surface has on an occupant is to provide a tangential acceleration through friction. Then, because the tangential direction runs into the wall, the occupant is "thrown against the wall" ...


4

Let's assume for now that the item is in a circular orbit (just to keep things simple) The Gravitational Pull is counterbalanced by the Centripetal Force This sounds to me like a case of the anti-centrifugal brigage "correcting" a statement by replacing the word "centrifugal" with the word "centripetal" and, in doing so, turning the statement into ...


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Looks like you are thinking that motion should be along the line on which the Net Force lies as well as in the direction of Net Force. This is not necessary. Force is only supposed to change the velocity of the body. The resulting velocity is not necessarily/always along the line of acceleration i.e, change of velocity. The Centripetal force create ...


4

I think the statement in your book is false. The reason why one feels weightlessness in a satellite orbiting the earth can be understood in two ways: In an inertial frame attached with some distant stars. In the non-inertial frame of the satellite. (Strictly speaking, all the explanation I am giving is preRelativistic.) Looking from the frame of distant ...


30

The statement: The Gravitational Pull is counterbalanced by the Centripetal Force is rubbish. The satellite undergoes a centripetal acceleration because it is acted on by the gravitation force. Some people call the force which causes a centripetal acceleration the centripetal force. So in such a case the gravitational force and the centripetal force are ...


1

If I understand your description ("the tube is on an angle") correctly, then the "outer" wall of the tube is where the centrifugal force is pointing - and the "inner" wall is the opposite side. When the tube is spinning, there will be an apparent radial force on all the particles - the lighter particles will experience a "buoyancy" towards the inner wall, ...


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The ship can apply thrust along +x,-x,+y,-y,+z & -z. After reaching a velocity $v$ in the +x direction, the thrust is switched off. Now if thrust is switched on along -y direction, the body will first traverse a curved path during acceleration until it makes an angle with the +x direction attaining some velocity $v'$ in the +y direction when the thrust ...


0

You refer to the observer with the absolute position. I know what you mean. Let us called that “laboratory coordinate system”. In principle each inertial system is equivalent to all other ones (as long as they are at rest or moving continuously). People tried to establish an absolute coordinate system but you cannot find any such system. However, you can ...



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