1. L

    turbulent velocity profile

    I cant understand that the( in the second picture) logarithmatic law velocity profile is quite accurate for y larger than 30 , but neither velocity profile is accurate in the buffer layer ,, 5 <y<30 . Can someone help to explain it ? How do the author know that it's not accurate for 5 <y<30 ...
  2. P

    Formula For Horizontal Velocity

    Hi, just wanting to know if I am using the correct formula. A thrown ball, given the distance thrown and time in the air. Vx0 = x/t Initial Horizontal Velocity = distance thrown / airtime ?
  3. L

    velocity profile

    in this notes , I was told that the fluid particle moves along the streamline with the constant velocity profile . What does the velocity profile means here ? the horizontal lines inside the U-shape ? or the whole U shape and the series of lines ? just like the second photo
  4. L

    velocity gradient

    why the velocity gradient is given by the formula u(y) = y(V) / l , why not V / l ?
  5. L

    velocity after first and second collision

    three small spheres, A , B and C with mass of 3kg , 4kg , 7kg respectively are arranged as shown in the figure. Initially , sphere B is placed in static condition,while the sphere A is moving with a velocity of 4u towards B and collides . Then , sphere C move to right with velocity u , the...
  6. L

    determine the velocity after collision

    three small spheres, A , B and C with mass of 3kg , 4kg , 7kg respectively are arranged as shown in the figure. Initially , sphere B is placed in static condition,while the sphere A is moving with a velocity of 4u towards B and collides . Then , sphere C move to right with velocity u , the...
  7. L

    finding time and velocity

    A motorcycle accelerates at 1.6m/s^2 to reach a velocity of 20m/s of distance 50m . Determine the initial velocity and time elapsed . to find the velocity , i have 2(1.6)(50) = (20^2)- (u^2) , u = 15.5m/s but i have problem of finding the time , why i cant use the eq of s= ut...
  8. K

    Projectile motion problem

    A 5kg object sits at the top of a hemispherical dome (no friction) with a diameter of 96m. A breeze causes the object to start sliding down the dome. a. Using the object as a projectile, find the hang time b. Find the horizontal component of the velocity of the projectile c. Find the...
  9. P

    Find the height and the velocity of the object

    A bolt is detached from the lower part of an elevator cabin that is ascending with velocity 6meters/second and for 3 seconds comes to the point from where the elevator started to ascend. Find: in which height is the end of the elevator in the moment when from it the bolt was detached. What is...
  10. D

    Velocity tranfers - momentum vs. energy

    I have a question over the problem below. I am missing something evidently because my mind cannot see where the mistake is. The problem is meant to be a transfer of energy problem so the thought is that the hammer hits a lever and transfers all the KE of the hammer to the puck. The...
  11. N

    Force/Velocity of a spring

    A spring with a force constant of 350 N/m is compressed 12 cm by a 3.0 kg mass. How fast is the mass moving after only 10 cm of the spring is released?
  12. M

    Water Velocity Out of 200m Pipe at 5 degrees

    A resovoir releases water into a 200 meter long pipe with 2m diameter. At 5 degrees relative to x axis so the drop is 200m (sin 5 deg) = 17.4m Since v o is 0 all I can solve for in this veolcity vector: v =(vx^2 + vy^2)^1/2 is for vy = (2gh)^1/2 = 18.4m/sec. Without vx how to solve for vz ...
  13. T

    Velocity and momentum help

    You throw a 0.42-kg target upward at 15 m/s. When it is at a heigh of 10 m above the launch position and moving downward, it is struck by a 0.338-kg arrow going 27 m/s upward. Assume the interaction is instantaneous. a)What is the velocity of the target and arrow immediately after the...
  14. T

    Velocity/time/acceleration of a sprinter

    A sprinter constantly accelerates for the first third of a 100m race to reach maximum speed, then continues at maximum speed for the remaining distance. He reaches the finish line in 10 s. Calculate his acceleration and maximum velocity. How would I go about doing this? Please help!
  15. L

    Velocity and Magnitude

    My question is this: An object initially at rest experiences an acceleration of 2.0 *m/s² for 6.7 s then travels at that constant velocity for another 8.0 s. What is the magnitude of the object’s average velocity over the 14.7 s interval? This question confuses me, am I supposed to first...
  16. M

    Mechanics Problem (objects on a slope + momentum and velocity)

    Hi guys. I'll make this as brief as I can. Attached is the problems I'm struggling with, and my attempt at an answer. I know it looks quite sloppy, but I've done several more pages in the past few hours and I'm essentially no further forward; attached pics are as far as I've gotten. Would...
  17. F

    Statement : Force does NOT produce Velocity

    Below is an excerpt from a physics book I was reading: " Newton's First Law describes what Natural Motion is . It says that objects,left to themselves, will move uniformly in straight lines and we cannot ask why! This means whenever they do something else, we should be able to ask why...
  18. B

    【exam] electron's angular velocity

    I only know w= eB/m, and how can I calculate dw? ------------------------------------------------ As described in the Bohr model, an electron is circularly orbiting a proton in a hydrogen atom with radius r and velocity v. The orbital angular momentum of the electron is in the + z...
  19. M

    Find the streamlines of the velocity field

    Hello!! I have to find the streamlines of the following velocity fields: 1. u=x(1+2t), v=y 2. u=xy, v=0 I have done the following: 1. dx/u=dy/v => dx/(x(1+2t))=dy/y => ln(x)/(1+2t)=ln(y)+c => y=Ce^(ln(x)/(1+2t)) => y=Cx^(1/(1+2t)) Is this correct?? 2. dx/u=dy/v \Rightarrow...
  20. kelsiu

    Average drift velocity of electron in conductor

    I have a question on the derivation of the average drift velocity in a conductor: drift velocity is the average velocity which a free charge moving in a conductor has due to the influence of an electric field applied to the conductor. In a metal, the free charge will be an electron. As they...