bodies Definition and 523 Threads

I am trying to derive the dynamic equations of an aerial vehicle with 6 degrees of freedom (a quadrotor to be precise). I am using - two coordinate systems: the Earth frame and the body frame; - the Euler-Lagrange formalism: generalized coordinates {x,y,z,phi,theta,psi}, respectively, the...

Homework Statement A steel girder with a mass of 1000kg and a length of 10m rests on a concrete slab, with 4m overhanging the edge. How far can a 100kg man walk on the girder? The Attempt at a Solution I supposed that the right end of the slab is the fulcrum (rotating point), and...

Hello. I have been folowing this forum for a while, but this is the 1st time I post. If I make any spelling mistakes, forgive me because I'm not an english born speaker. My problem is the following, I have to write this program in C, and the graphical part is to be made in allegro or...

Homework Statement The problem is this. We have a structure (see the attached image) and need to make freebodies of all of the members. 150 lbs are applied to the platform being lowered by the strings. We also need to figure internal stresses, but I think I can get those if I can understand...

Hi I was wondering how the gravitational force of attraction is related to centripetal acceleration for two bodies rotating around a point between them. Specifically how would you determine the centripetal acceleration of each body if their masses and the distance between them was given...

Is this black body radiation considered light? PS: Sorry, I spelt emit wrong:(

Okay, I am really interested in relativity, but very ignorant in it also. I already know you would divide regular space/time by √(1 - rs/r) rs = schwarzschilds radius r = radius of object from center of mass How would we define regular space/time in an equation? What units or...

Homework Statement Body A of mass 3 kg is moving int he x+ direction with a speed of 14 m/s. Body B of mass 4 kg is moving in the -y direction with a speed of 7 m/s. What are the x and y-components of the velocity of the CM of the two bodies? The answer is (6m/s,-4m/s). Homework...

Ok please can someone help or at least point me in the right direction with this question please? I have air flowing through a pipe which is heated to 477 degrees via burners on the outside. The pipe itself is heated to 550 degrees and there is a thermocouple inside the air flow. However, the...

Homework Statement A car turns a corner with a radius of curvature of 11.1 m while braking to reduce its speed. If the brakes generate an angular deceleration of 0.5 rad/s2 what is the magnitude of the acceleration of the car half way through the corner when the car's linear speed is 9.6 m/s...

I am interested in describing the heat transfer and temperature gradients within a mixture of independent radiating bodies. States like this occur in many systems and i have been having a bit of trouble modeling this simple scenario. An example of a system is charcoals within a BBQ, and also...

Why can’t a 300lb NFL lineman accelerate off the line and maintain equal speed with a 180lb wide receiver? I realize there is more mass to set in motion, but there is also a greater amount of muscle to move that mass. If the ratio of muscle to mass is the same in both men, shouldn’t speed be...

How biology can explain these 'Incorrupt Bodies': http://www.youtube.com/watch?v=F7uPLx8PM8c&NR=1&feature=fvwp

I've seen much mention in websites of matt black surfaces being better emitters of infra red than shiny silver ones so if a matt black and shiny silver surface are heated to about 100 deg C the black one will cool down more quickly as a result of this! Doesn't Wien's law state that the amount of...

whenever 2 bodies are in contact , why do they exert force normal to each other on each other , i mean the normal force .

This question concerns a paradox I've come up with in GR. If somebody could tell me where it breaks down, I'd be much obliged. Thank you! Assume there is spaceship A hovering above a black hole, and spaceship B further away from a black hole The black hole, A, and B are all lined up. (The...

Homework Statement http://www.hdimage.org/images/bgkkpt63ckx96gu3xgh.jpg Homework Equations aA = aA/B + aB VA = VA/B + VB The Attempt at a Solution After staring at this question for some time, I finally had a go and got an answer of 1.25 rad/s, which is incorrect. I am totally...

I have a sphere (mass m, radius r) whose centre of mass is r/2 distance away from its geometric centre. If it is kept on a smooth horizontal surface with the centre of mass at the same horizontal level as the geometric centre, what exactly is going to happen? Also, I need to find out the...

Homework Statement On a leveled base is a plank with a mass M = 2 kg, on the plank is a weight with a mass m = 1 kg. What limit must the force exceed, when we pull the plank in a horizontal direction for the weight to slip from the plank? Ratio of friction between the plank and the base is...

Homework Statement Block A has mass m = 4.0 kg, and block B has mass m= 2.0 kg. The coefficient of kinetic friction between block B and the horizontal plane is 0.50. The inclined plane is frictionless at the angle 30 degrees and Block A sits on it. The pulley serves only to change the...

What is meant by total negative energy associated with bound bodies like planets. and also total energy of the hydrogen atom is negative. I wonder how it could be? Because I believe whatever negative energy may be, It must only be associated with bound systems, and I don't think that an isolated...

Stupid question, but I am no Einstein. So why do all the bodies have it? Does enegry also have it? What's it caused of? Thanks in advance, fawk3s

Homework Statement A wrecking ball is hanging at rest from a crane when suddenly the cable breaks. The time it takes for the ball to fall halfway to the ground is 1.31sex. Find the time it takes for the ball to fall from rest all the way to the ground. I think the formula to use is...

The velocity of a diver just before hitting the water is -10.2m/s, where the minus sign indicated that her motion is directly downward. What is her displacement during the last 1.10sec of the dive? I tried to use dthe x=1/2(Vinitial + Vfinal)t=40.8 but it's wrong, what am i doing wrong??

The Einstein field equation for gravity uses the stress-energy tensor, rather than just mass, to determine the gravitational force acting between two bodies. When spacetime curvature is small and relative velocities are much less than the speed of light, this force is well-approximated by...

I just want to get my head straight on something with regards to relativity and gravity - I think it's a simple question (or rather has a simple answer!) so there's no trick agenda here. If I have two bodies orbiting each other in deep space - far enough out for other gravitational forces to...

Hi all, I was bored a little while ago, and somehow started thinking about the Big bang and all that fun stuff. I once heard it said that some of the galaxies near the end of the universe are at close to light speed. Now I'm not here to dispute that (would be nice if it were true though) but...

Homework Statement A cord is wrapped around the rim of a solid uniform wheel 0.250 m in radius and of mass 9.20 kg. A steady horizontal pull of 40.0 N to the right is exerted on the cord, pulling it off tangentially from the wheel. The wheel is mounted on frictionless bearings on a...

Hi All, I don't know whether this question makes any sense or not anyhow i will ask. For example, consider a ball which is attached at the end of the string and let us assume that this ball rotates in the uniform circular motion. Then the reason it rotates in uniform circualar motion is...

Homework Statement A block of material of mass m and specific heat c falls from height h and reaches speed v just before striking the ground. Its temperature is measured immediately after it strikes the ground. If we ignore any change in temperature owing to interaction with the air, the...

Homework Statement okay, I know it says be descriptive and all, but I'll present a watered down problem with some insignificant data already calculated by me. my problem is to understand the logic behind the solution, I know the solution, I simply think my textbook is... false. here goes...

Homework Statement If an object falls five meters during the first interval of time, what is the total distance fallen at the end of the second interval of time? (Galileo's Theory of falling bodies) Homework Equations The Attempt at a Solution I know that at successive intervals of...

If an object falls five meters during the first interval of time, what is the total distance fallen at the end of the second interval of time? (Galileo's Theory of falling bodies) I know that at successive intervals of time the distance fallen is proportional to the odd numbers. So I suspect...

What will be the Gravitaional force between two bodies when the distance between them is zero e.g., If we place a ring around a sphere, the center of gravity of the two bodies coincide and thus the distance of separation is zero. F = G m1m2\d2 d = 0 ,F = Infinity

I have been reading about Acceleration Due To Gravity. All sources including Fundamentals Of Physics By Resnik say that ' Acceleration due to gravity does not depend on the object's properties like mass , density , shape etc '. The magnitude of 'g' is 9.8 m/s^2 for all bodies ? But I can not...

I have had this question for a very long time. Never got a convincing answer Every Heavenly body rotates about its axis. The sun, the planets, the galaxies, every heavenly body why is it so? what makes the rotate? ps:It is very likely that this question would be a repetition. If it is...

Homework Statement 2 bodies move towars each other M1 WITH Velocity V1 and M2 with velocity V2 ,on a frictionless surface with a spring between them(attached to M1),what will be the maximum contraction(I mean You know, shrink or W\E)? Homework Equations reduced mass...

I'd like to expand on the example Dweirdo set in his thread and ask a few different questions. I didn't want to hijack his thread as I thought it would keep info more organised if I separated the discussion. So, let's take the example that we have a black hole and two observers, one (A) far...

Homework Statement "Knowing that crank AB has a constant angular velocity of 160rpm counterclockwise, determine and plot, for values of \theta from 0 to 360 degrees, (a) the angular velocity and angular acceleration of rod BD, (b) the velocity and acceleration of collar D...

Hi How would I show that the centre of mass of two point particles, one of mass m1 and the other m2, when released from rest from infinite simultaneously, stays in the same place? I feel this is a very simple question, I just can't seem to get it right. Everything I've tried still involves...

Homework Statement A wrecking ball weighing 4800N is supported by a uniform boom of wieght 3600N. A support cable runs from the top of the boom to the tractor. the angle between the support cable and the horizontal is 32degrees and the angle between the boom and the horizon is 48degrees...

Homework Statement If the system is released from rest, determine the speeds of both masses after B has moved 1m. Neglect friction and the masses of the pulleys. http://img14.imageshack.us/img14/6321/fbd.jpg The Attempt at a Solution I have drawn up the free body diagram for both...

If both bodies are in motion and come into contact, say a ring sliding on a block in motion as well. The speed of the ring (RPM) and the speed of the block in motion would both change once the bodies come into contact. Is there a way of calculating what the speeds of both bodies would be...

Hi, Maybe this is more a mechanical question, but here goes. In a ring on block wear test, if both bodies are in motion, the speed of the ring (RPM) and the speed of the block in motion would both be differ on contact from what the were originally were. Is there a way of calculating...

Homework Statement Consider 2 magnetic masses, m1 and m2; these 2 repel each other for a distance s with force f (relative to each other)...which applies from m1 to m2. Predict final velocity of m1 and m2. Assume final distance to be v1 and v2 Assume the 2 masses at rest initially...

why do bodies at rest weight more than zero? here is the bull thing... now I am sitting on my chair and i know Earth exerts a force on me which is called my weight. by definition w=mg I DO NOT have any acceleration g or anything else. let me prove a = dv/dt my speed is zero v = 0, coz...

I'm currently writing a vehicle simulator and have constructed a chassis out of physical node bodies that are connected as in the screenshot below. I am trying to work out the normal force at each of the green circles such that if it were suspended by each of the four nodes, the summation of the...

(i) how you solved this problem, An object of mass 10 kg is dropped from a great height. (a) If the object is subjected to air resistance equivalent to 10 times the instantaneous velocity, find the velocity. (b) How far does the object drop after 5 sec? (ii) what you got as a solution...

I am having trouble on this problem. An object of mass 10 kg is dropped from a great height. (a) If the object is subjected to air resistance equivalent to 10 times the instantaneous velocity, find the velocity. (b) How far does the object drop after 5 sec? Ok so I thought the equation...

Hi there, I have to solve the following problem: A semi-infinite body x<0 has thermal conductivity K_1 , density \rho_1 , and specific heat C_1. It is initially at temperature T_0. At time t=0, it is placed in thermal contact with the semi-infinite body x>0, which has parameters K_2 , \rho_2...