Kinetic energy Definition and 1000 Threads

Homework Statement A tall, cylindrical chimney falls over when its base is ruptured. Treat the chimney as a thin rod of length 49.0 m. Answer the following for the instant it makes an angle of 32.0° with the vertical as it falls. (Hint: Use energy considerations, not a torque.) (a) What is the...

Homework Statement A 250 g object is dropped from a height of 150 m. What is the kinetic energy after falling to 100m Homework Equations V2^2 = V1^2 +2ad Ek = 1/2 mv^2 The Attempt at a Solution I used the kinematics equation to find my v2 then I used this to find Ek. I got the answer 120J but...

Homework Statement You stand at rest on one end of a 3.00m long platform (also at rest). The platform is on a smooth friction-less surface. If you walk from one end of the platform to the other at the constant rate of 2.00m/s, what is the kinetic energy of the system (you and the platform)...

Homework Statement An 1100-kg car traveling at 24 m/s coasts through some wet mud in which the net horizontal resistive force exerted on the car from all causes (mostly the force exerted by the mud) is 1.7 x 10^4 N. Determine the car’s speed as it leaves the 18-m-long patch of mud. m = 1,100...

http://i.imgur.com/0RtN9Ui.png?1 I am trying to find the linear velocity of the sphere as it leaves the cliff. 2. Homework Equations : Moment of inertia of a sphere: I= 2/5 mr2 3. My attempt at a solution: I know that I am supposed to solve this through the conservation of energy, but would...

Homework Statement The potential energy for a mss m = 1.0 kg moving in one dimension is given by U(x) = (2.5J) sin πx. The mass starts at x = 0 with an initial velocity v = 0.71m/s. (The plus sign means the motion is in the positive x-direction.) Describe the subsequent motion of the mass...

Homework Statement A charged particle (m=1.673*10^-27 kg) exists in a region with E=10 kV/m in the x direction and B=1T in the y direction. If the particle moves without being deflected calculate its kinetic energy. Homework Equations F=Q(E+u x B) and KE=1/2 mu^2 where u is velocity. This is...

i'm struggling to understand this: an alpha particle is emitted with a kenetic energy T, if we know the value of the depth of the nuclear potential well V, we find the kenetic energy of the alpha particle inside the nuclei by substructing V-T , would you please explain this to me? Thank's

Homework Statement [T,V]=[TV-VT]ψ Homework Equations T=(-ħ2/2μ)∂2/∂x2 V=(1/2)kx2[/B]The Attempt at a Solution [(-ħ2/2μ)∂2/∂x2((1/2)kx2ψ)]-[(1/2)kx2(-ħ2/2μ)∂2/∂x2(ψ)] I think my problem is with executing the chain rule on the first term: (-ħ2/2μ)[x2ψ''+2xψ'+2xψ'+2ψ-x2ψ''][/B] The x2ψ''...

Homework Statement An assembled system consists of cart A of inertia mA, cart B of inertia mB, and a spring of negligible inertia, clamped together so that the fully compressed spring is aligned between the front end of cart B and the back end of cart A. The internal energy of the system...

Homework Statement Edward and Jacob, standing face-to-face on a horizontal sheet of frictionless ice, push off each other, causing each to slide backward. Jacob is more massive than Edward. After the push, which of the two is moving faster? Homework Equations Conservation of momentum: Pi = Pf...

Homework Statement A 20.0 kg cannonball is fired from a cannon with a muzzle speed of 1000 m/s at an angle of 37.0° with the horizontal. A second ball is fired at an angle of 90.0°. (a) Use the isolated system model to find the maximum height reached by each ball. (b) What is the total...

I'm going through a physics exercise at high school level. A ball is dropped through a slide and when it reaches the bottom of the slide it will travel horizontally. Assuming there is no energy loss due to friction or air resistance draw a velocity time graph. I tried working it out, the answer...

Hello, I have a question regarding one of the questions on a sample exam I have for an upcoming test tomorrow. For question 2, I attempt to use the Kinetic Work Energy theorem to solve for the Work done by friction, but I don't get a correct answer. As you can see, I attempted certain things...

How would one find the reference frame in which an object [which undergoes a perfectly inelastic collision with a second object] experiences no change in its kinetic energy?

Hi there, I've been given a statement in which I need to find out where Kinetic Energy goes when a moving lorry breaks to avoid a collision?There are no equations given. Only information needed to complete the question.I have tried looking around the internet to see what the possible answer...

When calculating the total kinetic energy do i have to take into account the rotational kinetic energy of the wheels?

Would there be any way to get the energy from the rotation of a planet, which is an Earth like planet in material, sized like Jupiter, and seems to have a 24 hr day. I am just starting to get into real Physics, So I am not even sure where to start getting the numbers to work with, and I would...

Homework Statement A block with mass m rests on a smooth, frictionless ramp with mass M and height h. The ramp itself sits on a frictionless horizontal surface in which it is free to slide. The block slides smoothly down the ramp from rest. We want to find the speed of the block after it has...

Homework Statement Not a homework or coursework question, but given the simplicity of the problem I feel that this is an appropriate subforum. Consider a person spinning a rock on a string above their head at a constant angular velocity, walking away from the observer at a constant linear...

I would like to know if kinetics energy of a disk with radius 'r', mass 'm' which turn around itself at Wb (relative rotation) and which turn around blue axis at distance 'd' is : 1/2md²Wa²+1/2mr²(Wa−Wb)² ? With Wa > Wb Look at image please.

Homework Statement Hello, first year engineering student here :)https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpf1/v/t35.0-12/10744040_871781156179440_107104578_o.jpg?oh=73c4261941e7ef6b7c682558c0925a63&oe=544F5CA4&__gda__=1414428985_0415c28b8b2e194bf0b57f065267fe49 [/B] The question is...

Homework Statement When a 7 3 Li nucleus is bombarded with protons α particles emerge.Calculate the kinetic energy of the alpha particle assuming the kinetic energy of the bombarding proton to be negligible. Given M (7 3 Li)=7.016004a.m.u. M (p)=1.007826a.m.u and M (α)=4.002603a.m.u. Homework...

1. The problem statement & given/known data A neutron star is a collection of neutrons bound together by their mutual gravitation. The density of such a star is comparable to that of an atomic nucleus (10^17 kg/m^3). a) Assuming the neutron star to be spherical in shape and of uniform mass...

I have been studying the Work and Energy chapter of physics and am currently confused on when to make work equal potential energy and when to make it equal to change in kinetic energy. Some of the problems have the work equal to change in KE and some have it equal to PE. For example, why is...

While I am familiar with the derivation of the relationship between mean translational kinetic energy, ##<E_k>##, and temperature, ##T##, for an ideal gas (namely ##<E_k> = \frac{3}{2}k_B T##); I fail to see how we can establish such a relationship for solids, liquids, and even real gases. Could...

Homework Statement A 2000kg car is moving at 50km/h. What is the force required to stop it? Homework Equations KE=1/2m(v^2) p=m*v The Attempt at a Solution 1/2(2000kg)*(50km/h)^2 = 1000kg*2500km^2/h^2 = 2,500,000 km^2/h^2 converting from hours to seconds and km to m (to get joules)...

I know that momentum is conserved when no "net" external forces such as Friction, Gravity, and air resistnace normal force; However, during inelastic collisions it says kinetic energy is not conserved because of external forces as well. 1. Are the external forces different for mechanical energy...

Homework Statement An asteroid of mass m = 2.6 × 10^6 kg approaches the Earth. When it is exactly 3 Earth radii away from the Earth's centre its speed relative to the Earth's centre is u = 8.7 × 10^3 m s–1. The asteroid subsequently falls down to the Earth's surface. You may assume that the...

Homework Statement An asteroid of mass m = 2.6 × 10^6 kg approaches the Earth. When it is exactly 3 Earth radii away from the Earth's centre its speed relative to the Earth's centre is u = 8.7 × 10^3 m s–1. The asteroid subsequently falls down to the Earth's surface. You may assume that the...

Homework Statement The nuclear masses of parent and daughter nuclei are Mp= 226.025 amu and Md=222.017 amu.Mass of alpha particle is Mα=4.002amu.Find qvalue and kinetic energy of alpha particle emitted for the alpha decay. Homework Equations Q=(Mp -Md-Mα)amu...1 Assuming nucleus to be at rest...

Please help! I have a test tomorrow. 1. Homework Statement A car with a weight of 15,000 N moves horizontally at 30 m/s. a) What is the car's KE? b) What will be the magnitude friction force to stop the car over a 60m distance? Homework Equations F=ma KE=1/2*m*v2 The Attempt at a Solution a)...

Homework Statement A uniform wheel of mass 10.0kg and radius 0.400m is mounted rigidly on a massless axle through its centre. The radius of the axle is 0.200m, and the rotational inertia of the wheel-axle combination about its central axis is 0.600kg.m2. The wheel is initially at rest at the...

Homework Statement A mass m = 77 kg slides on a frictionless track that has a drop, followed by a loop-the-loop with radius R = 15.1 m and finally a flat straight section at the same height as the center of the loop (15.1 m off the ground). Since the mass would not make it around the loop if...

Homework Statement When lights falls on metal suface , electrons are emitted if the wavelength of light is less than or equal to λ , .If lights of 0.5λ is used , then maximum kinetic energy of electrons is E . if lights of 0.25λ is used , what's the maximum kinetic energy of the electron...

Homework Statement since the bombarding electron has only 7.0eV ... it's not sufficient for the electron in the ground state to be excited which needs 10.4eV , so no excitation occur. and in my opinion, the bombarding electron should emerge with the same amount of energy ... but the ans given...

A block of mass 10 kg is pulled 5 m upwards along a rough surface at an angle of 20 deg, an external force of 100 N and vi = 1.5 m/s. The coefficient of friction is 0.4. Calculate: 1) The work done by gravity 2) The increase in internal energy between the block and the surface as a result of...

HI, I have been going through dirac's paper on quantized singularities in the electromagnetic field and there he referred to a problem of negative kinetic energy of electron, what does it mean? I am going to make a presentation on magnetic monopole next month so I need an explanatory answer...

Just wondering if apparent weight affects kinetic energy or is it only mass that affects it regardless of apparent weight? for example, a helicopter is falling but is providing a small thrust. say the helicopters mass is 50kg and it provides 100N of thrust upwards therefore, using w=mg, the...

Homework Statement An inclined plane of angle θ = 20.0° has a spring of force constant k = 460 N/m fastened securely at the bottom so that the spring is parallel to the surface as shown in the figure below. A block of mass m = 2.51 kg is placed on the plane at a distance d = 0.324 m from the...

Homework Statement What is the kinetic energy of an electron with a momentum of 40 GeV/c? The Attempt at a Solution Kinetic energy involves velocity of the particle so my first thought was to write momentum in terms of velocity. p = \frac{mv}{(1-(v/c)^2)^{1/2}} p^2 = \frac{(mv)^2}{(1 -...

Homework Statement Show that 1/2mγv^2 does not give the correct kinetic energy. Homework Equations 1/2mγv^2 γ = 1/(sqrt(1-v^2/(c^2))) The Attempt at a Solution Well, since the classical mechanics version of kinetic energy was the integral of momentum with respect to v, I felt I could...

Is there a way to transfer kinetic energy between two objects without the objects touching one another?

Net Work = Change in Kinetic Energy. What about potential energy? Homework Statement When we say net work = change in kinetic energy, does that mean that if the height of an object changes (and its initial and final velocity) do not change, then the work done also equals the potential...

Please could someone explain the following situation. A truck weighs 4 tonnes and travels at 18m/s. A car on the same road, weighs 1.4 tonnes and is traveling at 35 m/s. The car has more kinetic energy but less momentum. My book says that momentum is how hard it is to stop something which is...

Homework Statement http://puu.sh/bz0km/092f2d8781.png Homework Equations h^2/2ma^2 The Attempt at a Solution I've found the uncertainty of the kinetic energy through many means, and I'm confident that it's .052MeV. The easiest method that gave me this answer was: using...

Homework Statement A motor imposes 5 Nm on a shaft of a 100kg flywheel which is 80cm(diameter) What is the rotational kinetic energy after 10 mins? assuming the flywheel was at rest and the mass moment of inertia of the shaft is negligble. Homework Equations Ig=1/2 * mr^2...

For the following system, what is the total KE? I have the following \[ \frac{1}{2}m_1\dot{x}_1^2 + \frac{1}{2}J_1\dot{\theta}_1 + \frac{1}{2}J_0\dot{\theta}_0^2 + \frac{1}{2}m_s\dot{x}_s^2 + \frac{1}{2}J_s\dot{\theta}_s^2 \] \(J\) is the mass moment of inertia.

Homework Statement Hi guys! I have a problem pertaining to the kinetic energy gained by a point charge from interacting with a another point charge. Here's the problem: A point charge of mass m1 and charge q is placed near another point charge with mass m2 and charge Q. Both charges are of...

I solved the problem myself immediately before anyone replied.