Kinetic Definition and 1000 Threads

Homework Statement A 3-kg mass is attached to a light string of length 1.5 m to form a pendulum. The mass is given a initial speed of 4 m/s at its lowest position. When the string makes and angle of 30° with the vertical, find (a) the change in potential energy of the mass, and (B) the speed...

Can you explain me this: Ferromagnet has permanent magnetic force and can't lose it in the constant conditions, so if i put magnet and piece of the metal it will be pulled away from the magnet creating some kinetic energy. As energy can't be created, just transfered, so I don't understand who...

Homework Statement A sled and its rider have a mass of 90 kg and a speed of 3 m/s at point A on the frictionless hill of Figure 5.25. At the bottom of the hill, the sled moves onto a rough surface with a coefficient of friction of .6. How far from the base of the hill will the sled move...

Homework Statement A simple pendulum is constructed by supporting a .375 kg steel sphere by a thin string 1.2 in length and of negligible mass. The pendulum is released form rest at a position where the string makes an angle of 35° with the vertical. What is the speed of the sphere as it...

When water is vigorously shaken the kinetic energy and, hence, the motion of the molecules increase. Which particular forms of energy do increase : the translational energy (is this the energy associated with the collision and the chaotic random motion of the water molecules ?) or also the...

There is this equation: E=h*f that give us the energy of each photon. If we want to find kinetic or dynamic energy,what equation we will use? Something like K=1/2*m*v^2 (where v is the speed and we have v=A*cos(t/T- x/λ)) ?

Homework Statement A car is traveling at a given velocity on a road with a coefficient of friction of 0.5 when it suddenly has to apply the brakes. Given that it travels 10 meters before coming to a stop what is the initial velocity of the car? Homework Equations Vi^2=Vf^2 + 2ax...

Homework Statement A 50 gram steel ball moving on a frictionless horizontal surface at 2.0m.s^-1 hits a stationary 20 gram ceramic ball. After the collision the ceramic ball moves off at a velocity of 2.5m.s^-1. (i) Calculate the velocity of the steel ball after the collision. (ii) Calculate...

Homework Statement (The picture is not from my textbook) A Faraday Dynamo is used as a brake. The brushes are connected with an external resistance R_\Omega. The circular disk has mass m, and angular velocity \omega_0 when t = 0. a) How long does it take until the kinetic energy of the disk...

Homework Statement Using the relation ## tan \theta = \mu_k ## what angle should the rope make with the horizontal in order to minimize the work done per unit distance traveled along the ground. Homework Equations ## W = Fdcos\phi ## The Attempt at a Solution I found...

Homework Statement Find the applied force for a object if the coefficient of kinetic friction equals 0.30 and the acceleration equals 5m/s^2. The applied force makes a 40 degree angle with the horizontal. The mass of the object is 10kg. Homework Equations Fnet=ma The Attempt at a...

Homework Statement A solid, Uniform disk of radius 5.00 cm and mass 1.50 kg is rolling without slipping a long a horizontal surface. The disk makes 2.00 revolution per second a. Find the total kinetic energy (translational + rotational) of the disk b. Find the minimum height h of the...

My mcat book says temperature is a measure of the total kinetic energy of a system. Then later on it says temperature is a measurement of the average kinetic energy of a system. Is this an error? Thank you.

Homework Statement A 100 N force directed 37° below the horizontal is applied to a 30 kg object on a horizontal surface. If the magnitude of the acceleration of the object is 1.3 m/s2, what is the coefficient of kinetic friction (μk) between the object and the surface? Homework Equations...

I read that based on temperature , electrons have kinetic energy in metals so they randomly move around the ion lattice. when we apply current to a room temperature conductor, the electrons being charge carriers align and form current? but what happens in the plates of a capacitor , when the...

Hi, all. Here is an expression about kinetic energy from analytical dynamics of Haim Baruh which confuses me. "Consider a particle and the case which the kinetic energy is only quadratic in terms of velocity of the particle. We take the differential form of work-energy principle and remove...

So my professor said that the Kinetic energy of the particle in a 3D infinite well is dependent on position where in a 1D infinite well it's NOT dependent on position. She is sort of notorious for being wrong apparently and many of my undergrads are telling me she is wrong. I understand that...

is it related to fermi energy? what is the exact equation form?

Are there any good books to understand the BBKGY equations of kinetic theory?

Hello folks! I have just come from a night at the pub with fellow students of life where over many a pint several mysteries of the universe were discussed. One of my friends asked me a question concerning special relativity that initially took me by surprise and which has me wondering about the...

This has been bugging me. Several respected propulsion scientists at the 2008 Joint Propulsion Conference claimed that interstellar travel within a human lifetime was impossible. The KE of a rocket traveling at a significant fraction of c would be enormous via KE=0.5 * m * v^2 and that...

Hi I need some help explaining kinetic moment and moment of the center of mass. This is an example: http://session.masteringengineering.com/problemAsset/1529176/3/Hibbler.ch17.p107.jpg Okay I know that when you do moment equations: The Moment forces about some point is = to the kinetic...

If thermodynamic temperature can be interpreted as the average kinetic energy in a system, is there a quantity defined as the standard deviation? For example, let's say you poured some hot water into a cup of cold water. The instant you poured it the standard deviation of the system would be...

Homework Statement A horizontal 845.0 N merry-go-round with a radius of 4.3 m is started from rest by a constant horizontal force of 74.0 N applied tangentially to the merry-go-round. Find the kinetic energy of the merry-go-round after 2.2 s. Assume it is a solid cylinder. The...

Homework Statement A computer scientist has dropped a tiny pizza crumb onto a magnetic disk. Later, when it's turned on, the disk is rotating at 88 revolutions per second about its axis, which is vertical. The coefficients of kinetic and static friction between pizza crumbs and the disk are...

Linear Momentum question - help please Homework Statement A 15,000 kg loader traveling east at 20 km/h turns south and travels at 25 km/h. Calculate the change in the loader’s kinetic energy. linear momentum. Homework Equations KE2-KE1 = change in KE p=mv The Attempt at a Solution a...

Homework Statement Blocks A and B are moving toward each other. Block A has a mass of 2.0 kg and a velocity of 50 m/s, while B has a mass of 4.0 kg and a velocity of -25 m/s. They suffer a completely inelastic collision. The kinetic energy dissipated during the collision is: Homework...

Homework Statement At what energy does an electron become “relativistic”? Consider electrons with kinetic energies of 50 eV, 50 keV, and 50 MeV. For each case, calculate the momentum of the electron first using the non-relativistic formula for kinetic energy, and then using the correct...

I read in a science magazine that you would be able to generate more energy by collecting a mass of water and tipping it through a turbine than from generating energy from the impact of that mass of water as individual raindrops. Now this may simply be to do with the technology we have that...

When does the Kinetic Work Energy Theorem not apply to a situation? Or better, is there a general form of the equation where work can equal the change in any energy? What is work besides a force and a distance?

Homework Statement An ice block is being pushed through a displacement d→=(15m)i -(12m)j along an embankment with rushing water. It exerts F→=(210N)i -(150N)J on block. How much work on block does force do? Homework Equations W=Fxd Pythogoreum equation a^2 +b^2= c^2 The Attempt...

Homework Statement A bullet of mass 4.2 g strikes a ballistic pendulum of mass 2.0 kg. The center of mass of the pendulum rises a vertical distance of 18 cm. Assuming that the bullet remains embedded in the pendulum, calculate the bullet's initial speed. Homework Equations The...

Hi all! I have a problem on finding the first passage time for kinetic monte carlo model. Suppose I have a linear kinetic model for n states: S1<->S2<->S3<->...<->Sn where all the rate constants k_ij for transition between any two states are known. Is there any general way to find out the...

Homework Statement If the velocity of a rocket is 10 meters per second and its mass is 10 kg, its kinetic energy is: a. 5000 joules b. 500 joules c. 10000 joules d. 1000 joules [b]2. Homework Equations [/b) Ek= (1/2) mv2 The Attempt at a Solution e=(.5)10x10(2) E=5000 j

1. Homework Statement What type of energy does a blackboard eraser have when I hold it steady three feet about the ground? a. potential energy b. kinetic energy c. electrical energy d. spring elastic energy I think it is kinetic energy. But I am confused on the differences of...

If I needed to calculate the kinetic energy of a bar suspended by a rope at one of its ends, in other words, a bar pendulum, do I need to calculate the kinetic energy of the center of mass plus the kinetic energy relatively to the center of mass or do I need to calculate the kinetic energy of...

"A hockey puck is hit on a frozen lake and starts moving with a speed of 12 m/s. Exactly 5.0 s later, its speed is 6.0 m/s. What's the puck's average acceleration? What is the coefficient of kinetic friction between the puck and the ice?" I've calculated the acceleration, but I'm stuck when it...

Homework Statement A 100 kg refrigerator is on rest on the floor.How much work is needed to move the refrigerator at a constant speed for 6 m along with a floor friction force of 200 N ? Homework Equations I used ΔK = W(Fg)+ W (N) + W(f)+ W(T) =0 and W(Fg)+ W (N) = 0 so W(T)=-W(f)=f*...

Homework Statement A 23.0 kg child plays on a swing having support ropes that are 2.10 m long. A friend pulls her back until the ropes are 41.0-degrees from the vertical and releases her from rest. a.)What is the potential energy for the child just as she is released compared with the...

Homework Statement I don't know how to solve this question. 28.8J of work were done in accelerating a mall of 1.8 kg from rest. Find its final velocity. I'm not sure which formula to use..Homework Equations F=ma W=Fs KE=1/2 mv^2The Attempt at a Solution I can't figure out which formula to use...

Homework Statement A ring of mass Mb, radius b, is mounted to a smaller ring of mass Ma, radius a and with the same centre, and they are free to rotate about an axis which points through this centre and is perpendicular to the rings. Dust of mass Ms is distributed uniformly on the inner...

Homework Statement With the work function of copper being 4.65eV calculate the kinetic energy of a photoelectron knocked out with a photon with wavelength of 200nm . Then calculate the velocity of the electron.Homework Equations KE=hf-ø The Attempt at a Solution FIrst time I have done a...

Homework Statement A 5kg ball (m), is to be dropped 1 meter (h) in a vacuum with no resistance in the Earth's gravity (g). Use the speed and motion equations to show that its KE at impact is equivalent to its PE at its starting point. Homework Equations PE = mgh KE= 1/2mv^2...

Hi everyone, I have a question on the rate constant of a kinetic model(like the one we use in describing chemical reaction). Suppose we have the following model between two states A and B: A--(a)-->B A<--(b)--B where a, b are the rate constant for the transition. So the corresponding...

If an electron is traveling at C/2, the Lorenz formula says that mass is about 1.15 me, do we get the value of KE simply multiplying 1/2mv2 by 1.15? Is it as simple as that?

Homework Statement a rocket explodes in flight into two equal mass pieces still going in the same direction with one piece moving twice as fast as the other. What is the ratio of the total kinetic energy of the pieces just after the explosion to that of the rocket just before? Homework...

Homework Statement Finding error in kinetic energyHomework Equations K = \frac{1}{2} m v2The Attempt at a Solution Measured mass and velocities have errors in them. So we have to use derivative method to calculate uncertainty in KE which is to find the square root of the derivatives of K...

A 10kg block is at rest on the floor, and then a force of 30 N pushes on the block horizontally. If the coefficient of static friction between the block and the floor is μs= 0.33 and the coefficient of kinetic friction between the block and the floor is μk= 0.20, what is the acceleration of the...

Homework Statement A 5.0 kg box slides up a 10 m long frictionless incline at an angle of 20 degrees with the horizontal, pushed by a 40 N force parallel to the incline. What is the change in kinetic energy? Homework Equations Ek = 1/2 mv2 Ep = mghThe Attempt at a Solution I tried to assume...

Homework Statement At what rate does the solar wind carry kinetic energy away from the sun? Give your result first in watts, then as a fraction of the Sun's luminosity in photons, L=3.8*10^26 W Homework Equations KE=(1/2)mv^2 mass loss of sun- Msunloss=4πr2vρ The Attempt at a...