1. J

    Find tension in a string with attached body doing UCM

    Problem A rock with mass 1.5 kg is being whirled in a horizontal circle on a string 0.8m long. The speed of the rock is a constant 5m/s. Find the magnitude and the direction of the tension in the string. There seems to be too many unknowns here to solve??(Sadsmile) Answer 49N @ 17...
  2. R

    Free Body Diagram

    Please , could any body help me to draw the free body diagram for the below problem ? assume that the static friction coefficient between the sloping beam and the ground is us . Thanks in Advance
  3. L

    The potential energy of born rigid body is a constant ?

    \ \ \ \ \ The sum of rest masses of a born rigid body consists of two parts: the potential energy of a born rigid body, and the actual particles or the material in the form of physical existence. \ \ \ \ \ For a born rigid body, there is no conversion between matter and energy. The actual...
  4. M

    Deriving an expression for Radiation Pressure from Black body function Hello, I am reading a book about Stellar Structure and Evolution and it takes an expression for the Black body function in terms of frequency and substitutes it into a 'Pressure Integral' to derive an expression for Radiation Pressure. It just...
  5. G

    Free body diagram

    Greetings! I could need some help on the following problem. 1. Explain force and momentum equilibrium for a free body and the division of forces in composants. Show how these are used to determine the forces on the two rods in the figure. 2. Explain what tension there are in the rods...
  6. S

    Calculating "g - force" acting on an Human Body

    Dear friends, I want to know the total g-force acting on an Human Body while accelerating. Weight of the Human Body = 70 Kg; Initial Velocity (Vi) = 0; Final Velocity (Vf) = 22.22 m/s; Start Time (ti) = 0 sec; Final Time (tf) = 1 sec; delta V = Vf-Vi = 22.22 m/s - 0 = 22.22 m/s delta t = tf -...
  7. L

    Calculate a derivation of a the angular speed of a solid body

    I am practicing for a mechanics exam. Please find the problem and solution in the image: I am not able to reach the solution. The question is to derivate an expression of the angular speed to obtain the angular acceleration. The angular speed is a function of the rotation angle, so...
  8. J

    Moment of inertia of a compound body problem

    Hi everyone, I wonder if anyone can help me with a problem which has had me stuck for some time. The problem is as follows - PROBLEM A thin, flat, uniform disk has mass 'M' and radius 'R'. A circular hole of radius 'R/4' centred at the point 'R/2' from the disk's centre is then punched...
  9. J

    Moment of inertia of a human body

    Hi everyone, I have come across a problem and I just don't know how to start to tackle it. The problem is as follows :- Estimate your own moment of inertia about a vertical axis through the centre of the top of your head when you are standing up straight with your arms outstretched. Make...
  10. J

    Moment of inertia of a compound body

    Good morning all, I am having trouble with a problem to calculate the Moment of Inertia of a body made up of two distinct but linked extended bodies. I have used the generic equations for these two bodies and then added the values to obtain what I thought was the solution but my answer does not...
  11. M

    Can some body explain how the spin on the ball is accelarated

    Hi , I am not very good at physics , But it would be appriciated if some body explain how and why the spin (revs) on the ball is getting faster (accelarated) between the ball leaves the hand and pitched to the ground in the video from 1:18 to 1:30
  12. B

    Torque and forces on a rigid triangle body

    Hello everyone, I am not a physicist or student so hoping someone here can help me verify my understanding of calculating torque and forces on a rigid body for a personal project I'm working on. I have the following rigid triangle, made of steel. It has 3 forces working on it. FL is a rod...
  13. O

    Electrical circuit closing through body

    Hello. I have a couple of questions. 1.) Hypothetical situation: If I touch a live mains wire (not a closed circuit, just one wire sticking from the socket) electricity is not going to flow through my body which is not grounding because I'm on the 4th floor on my building. So I would not get...
  14. L

    floating body

    why the floating body still stable when G ( center of gravity ) is above the B ( center of buoyancy)
  15. L

    free fall fluid of body

    why when the fluid container is accelearting upward , the pressure gradient in z direction is -2 ρ g ?
  16. E

    Thermal expansion of a solid body

    Hello, I suddenly feel quite confused with the simple equation of a body length (1d case) after being exposed to a temperature difference : L_final=(1+alpha*dT)*L_initial while dT is the temperature difference I try to use this equation twice - 1. I want to find the length of a body...
  17. T

    kinetic energy of a falling body in water

    Hi I am considering the impact energy of an object hitting me on the head travelling vertically downward with impact velocity v in water. The mass of the object is m, and the hydrodynamic added mass from the displaced water is "ma". I believe the kinetic energy at impact is KE=1/2 (m+ma) v*v...
  18. D

    Outward energy flux within a radiating black body?

    Given a black body radiator in thermodynamic equilibrium that is emitting electromagnetic radiation at some temperature, one might expect that there would be a constant energy flux from the interior of the body toward the surface to compensate for electromagnetic energy lost from the surface...
  19. T

    Help with free body diagram for a pendulum

    I wrote the summation of forces perpendicular to the inverted pendulum and the summation of the moments about the centroid of the pendulum. I am not sure if they are right (especially the signs) and was wondering if someone could check
  20. M

    When EM wave is hiting body we have New wave

    ***************************************************************************** James Clerk Maxwell, in 1861–64, published his theory of electromagnetic fields and radiation, which shows that light has momentum and thus can exert pressure on objects. Maxwell's equations provide the theoretical...