Velocity Definition and 1000 Threads

Homework Statement Consider the elevator and screw in Example 2-17. Assume the velocity of the elevator is 16 mls upward when the screw separates from the ceiling. (a) How far does the elevator rise while the screw is falling? How far does the screw fall? . I have only problem second part of...

I have a problem where I have a large mass on wheels that I want to power with an electric motor. My hope is that I can find the torque i need to start and drive the motor and this is what I have so far. Mass = 400t. Initial velocity = 0 Final velocity = 2.5m/s Distance required to travel =...

Homework Statement A ball is launched at 10 meters per second at an angle of 45 degrees above the horizontal. What was the duration of the ball's flight? What was it's highest point? When? What was the total distance traveled? Assume air resistance is negligible. Upwards and rightwards are...

Homework Statement A body of mass m, moves with a velocity v, and has a certain kinetic energy. What velocity would a body of twice the mass have to move to have the same kinetic energy. Homework Equations K.E=1/2mv2 The Attempt at a Solution I made an equation 2m1/2*v12/2= m2v22/2 from here...

Homework Statement An ant clings to the outside edge of the tire of an exercise bicycle. When you start pedaling, the an't speed increases from ) to 10 m/s in 2.6 s. The wheel's rotational acceleration is 13 rad/s^s. Determine the average tangential acceleration of the tire. Homework...

According to what I've been taught, the distance-related redshift seen by Edwin Hubble is an artifact of an expanding Universe. That is, as light travels through space, space itself expands, redshifting the light (matter is embedded in space and does not itself expand but is instead carried...

dear sir, light travels with constant speed of 3 x 10^8 m/s. does that mean light is in absolute motion irrespective of the its source?

Homework Statement Calculate the speed of sound in the classroom. You can use: Tuning forks, water, beaker, pvc pipe, ringstands, etc. Homework Equations v = f(wavelength) For fundamental frequency: L = 1/4(wavelength) For fundamental frequency: f = v/4L The Attempt at a Solution Here is...

How does this version of the power equation relate to physical situations? Does the value you get give you an instantaneous power? Or is the velocity to be taken as the average velocity (an actual displacement over time)?

I have seen this equation used to calculate the velocity of a projectile being launched off a table top. Where D=horizontal distance travelled, h=table height, and g=gravitational acceleration. Nowhere else can I find a calculation of velocity based on only two distances and GA. Everything I...

HI, I have read about tensors and generally understand the concept. One core thing about Vector/Tensor as I understand it is that its magnitude and direction should not change with change in coordinate system. I get that when I write vector and also when I use matrix transformation. However...

A catapult is pulled back 10cm with a force of 30N. How fast does the stone of mass 0.5kg got at maximum speed assuming no air resistance. I have absolutely no idea how to do this... But, I am assuming you use Ek=1/2mv^2, though I can't figure out how to apply it To rearrange that...

Homework Statement Derive an equation for the velocity vx(t), vy(t) of the particle. - my teacher writes this oddly, that means the velocity in the x direction at any point in time, and the velocity in the y direction at any point in time. Calculate the initial velocity of the particle...

When I rotate my head with 1rad/s , I can see a body which 350000km away have velocity greater than c.is that possible?

Hello! Would love a quick explanation of these two exercises :) 1. Homework Statement 1) Find objects acceleration, when mass is 200kg and it is being pulled on a horizontal plane with a force of 2000N. How much work is done on 400m road? 2) An object fell from 200m. How much of its energy...

For a vertical pipe of water can the pipe length affect the velocity of the water? note: the water is flowing through this vertical pipe.

I was reading that gyroscopes can be used to measure the angular velocity of precession, such as in the Hubble space telescope, but mathematically how can this be done? Many thanks

Homework Statement Rank the vertical component of the initial velocity of each projectile, greatest first.Homework Equations n/a The Attempt at a Solution I took the sine of the angles, the angles are ranked B>A>C>D you can see this visually as well as looking at the maximums. why isn't this...

Homework Statement So! The problem states that a grasshopper jumps from the edge of a table. We know that x-initial is zero and x-final is 1.06m. This is how far he jumped from the origin. The height of the table is unknown, but we know that the height of the grasshoppers jump with respect...

Homework Statement A bird can fly in still air at 100km/h. The wind blows at 90km/h from W(x degrees)S. The bird wishes to return to its nest which is due E of its present position. In which direction, relative to the air, should it fly?My textbook says that the velocity of the bird relative to...

Homework Statement A ball was thrown from a cliff, it reached to the ground after 2.5 seconds. a) Find the height of the cliff. b) Find the horizontal distance the ball reached. Homework Equations Δy = 2⋅g⋅t^2 Vfy = g⋅t √(Vfy)^2+(Vfx)^2 Δx= Vx⋅t The Attempt at a Solution I've found Δy=30.6m...

Homework Statement I don't remember exactly what the question was because it was on a quiz today. It said something along the lines of "a ladybug is on a turntable and begins to slip at .5 m/s. Find the coefficient of friction. Homework Equations Fc = (mv^2)/r a = v^2/r Ff = uFn I think...

This is just a reality that I have stumbled upon that I'm sure was well-known, but I still found it interesting. I apologize if this is second-nature to physics experts. I was responding to a post on a different thread that claimed you could make a tunnel around the Earth and if you sent a...

Homework Statement A wave pulse on a string is given by D(x) = D[0][/SUB]/(x[2][/SUP]+a[2][/SUP]), where D0 is a constant with units of cm3 and a is a constant with units of meters. a. If the wave moves along the string at a velocity of v in cm/s, what is the transverse velocity of particles...

Homework Statement Given a graph (see below) containing the velocities of two stars with respect to the sun, I am asked to calculate the velocity of the centre of mass of a binary system. I am not given the mass of either star, nor the shape of the orbit nor the velocity of the centre of mass...

Homework Statement Homework Equations [/B] T = inertia * alpha The Attempt at a Solution I'm not sure how the torque or angular velocity initially affects the time to speed, but it seems like the more angular velocity , then the quicker the engine would stop. I do know that more torque...

Homework Statement A projectile is launched: Horizontally, with an average displacement of 49 cm Vertically, with an average displacement of 28 cm At a 23 degree angle, with average displacement of 126 cm Homework Equations The Attempt at a Solution I am sad to say I don't know how to do it...

I'm reading Weinberg's QFT volume 1. At the end of section 2.4 he is deriving the Inonu-Wigner contraction where he reduces the Poincaré group to the Euclidean one by taking the low velocity limit. In analyzing how the operators depend on velocity there are some I understand and some I don't. I...

Homework Statement A comet orbits the sun. It's position in polar coordinates is given by, $$r(\phi)=\frac{1.8r_0}{1+0.8\cos{\phi}},$$ where ##r_0## is the position at closest approach. Its velocity at this point is given by ##v_0##. Use the concept of angular momentum to find the following...

Hi there, I'm struggling to distinguish why the following two equations are giving distinct answers, when the question explicitly states either could be used: v=u+at v^2=u^2+ad when v=12 m/s u=0 m/s a (average acceleration)= the unknown variable d=24 m t=4s Theoretically, the two should...

Hi! I've found some excercices and expanation of Work always consider a constant velocity, this is a net Force equal to cero. Like spring or gravity excercices related against a force applied. Does this relation with constant velocity has some usefull explanation why? Should I always assume...

Homework Statement In 1940, Emanuel Zachinni, one of a family of “human cannonball” performers, set a world record by traveling 53m. If he clears the 20 m tall ferris wheel (which is 25 m away from the cannon) by 10 m, how fast was he going at launch? Homework Equations range 53m...

I am trying to solve for Vy with given Vx. I know how to do this for the BLUE trajectory line, but I do not know how to solve this if there is an obstruction in the way (like the gray wall). My givens are: X1 X2 Y1 Y2 Vx Gravity Do I need to solve for the blue trajectory then adjust that for...

I read in several places that if, for example, a point particle exhibits uniform circular motion about the z-axis within an osculating plane not equal to the x,y plane, then the angular velocity still points along the z-axis, even though the angular momentum does not (it precesses about the...

I am solving a problem where I need to decide if an asteroids velocity is high enough to escape the planets gravitational pull. The way I did it was use conservation of energy and angular momentum to find an expression for the radial velocity and show that it remains positive as r tends to...

Homework Statement In a physics lab, 0.30 kg puck A, moving at 5.0 m/s [W], undergoes a collision with a 0.40 kg puck B, which is initially at rest. Puck A moves at 4.2 m/s [W 30 N] . Find the final velocity of puck B. Homework Equations Conservation of momentum Pythagorean theorum The...

So I read these two other threads: https://www.physicsforums.com/threads/relative-speed-of-two-cars.642873/ https://www.physicsforums.com/threads/two-cars-colliding.740948/ And gathered what I already thought was correct, that the relative velocities of two cars of equal mass crashing into...

Homework Statement [/B] A block travels in the positive x-direction with some velocity ##v_0##. It is subject to a drag force $$F(v)=-F_0e^{Kv},$$ where ##F_0,\,K## are positive constants. Find the point in time when the velocity of the block momentarily goes to zero. Find how far the block has...

Homework Statement A particle of mass 7.3 × 10−5 g and charge 24 mC moves in a region of space where the electric field is uniform and is 6.3 N/C in the x direction and zero in the y and z direction. If the initial velocity of the particle is given by vy = 4.1 × 105 m/s, vx = vz = 0, what is...

Homework Statement The water in the river moves southwest (45 degrees south of west) at 4 mi/h. If a motorboat is traveling due east at 15 mi/h relative to the shore, determine the speed of the boat and its heading relative to the moving water. Homework Equations Vector summation The Attempt...

Homework Statement If the velocity v of the air in a boundary layer having a dynamic viscosity of 18x10-6 kg/ms is given in terms of the distance y from the surface by v = ay + by2 where a and b are constants, calculate the surface shear stress if at 1.5 mm from the surface the velocity is 75...

Hello. I have a question. If I am moving with velocity v for an observer O. If I experience and kind if time dilation and my time slows down with respect to observer O's time. But if my time slows down. For O I will be moving slowly in time. If time dilation is large enough. I will almost freeze...

Hi, i need help in deriving the velocity potential of a moving 2D cylinder (circle) in potential fluid. The cylinder is moving in negative x direction U(t). I can derive the velocity potential of fluid past a cylinder (cylinder is stationary, in which it is the scalar summation of uniform...

Homework Statement Hello All, I might be at best HS level physics understanding but I’m quick study and need guidance. I am in a debate with someone who thinks a body can be crushed to the point of dust. I’d like to know if a comparison can be made, basic ratio: Human crushed by a building at...

Hello! I have some problems with geometry/kinematics, therefore i require in your help. :nb) I need to estimate the velocity of manipulator's grapple. I have found one solution (with the use of Jacobian's transformation), but i don't know, right it or wrong. Let's check together :wink: Maybe...

Homework Statement I am having trouble linking gravity to the radius of the Earth and angular velocity. I was using this as a solid method to confirm the equation for values of a different sort based on centripetal acceleration. When inputting the values though it does not add up and I cannot...

Hi, I appreciate any help. Thanks in advance! Homework Statement The image shows the top view of the set-up. Basically, it is a cylinder (resting on a horizontal plane) with two rods on either side attached in line with the centre of mass of the cylinder. Two pieces of string are then taped...

Homework Statement A boy release ball A from height 5m from ground at the same time other boy throw ball B vertically upward to exactly strike ball A. When ball B released it was 1m from ground find minimum initial velocity of ball b. Given g=10m/s^2 a) 2m/s b) 3m/s c) 4m/s d) 5m/s Homework...

Homework Statement Consider the surface, S, in the xyz-space with the parametric representation: S: (, ) = [cos() , sin() , ] −1/2 ≤ ≤ 1/2 0 ≤ ≤ os(). The surface is placed in a fluid with the...

Homework Statement Estimate the velocity of thermal neutrons at 25 degrees celcius Homework EquationsThe Attempt at a Solution I attempted to use KE=0.5mv^2 but I realized that I didn't know the Kinetic energy