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Energy

Energy Absorbance

A film badge worn by a radiologist indicates that she has received an absorbed dose of 2.3e-5 Gy. The mass of the radiologist is 67 kg. How much energy has she absorbed? Answer in mJ.

Answer in nm

A proton is located at a distance of 0.410 m from a point charge of +8.30 µC. The repulsive electric force moves the proton until it is at a distance of 1.56 m from the charge. Suppose that the electric potential energy lost by the system is carried off by a photon that is emitted during the process. What is its wavelength?

Atomic physics

Calculate the classical frequency for the light emitted by an atom. To do so, note that the frequency of revolution is v/2pir, where r is the Bohr radius. Show that as n approches infinity in f= 2pi2mk2e4/h3 times 2n-1/(n-a)2 n2 the expression varies as 1/n3 and reduces to the classical frequency.

Quantum Model

For two distinguishable, non-interacting particles in a box, Quantum Mechanics says the energy must be, for each individual particle, E = (h^2)/(8mL^2)*[(n_x)^2 + (n_y)^2 + (n_z)^2) where L is the length of one side of the cube, m is the mass of the particle, and the n's are independent integers that can take any value fr

Pogo Stick -- Kinetic Energy

Please see the attached file for full problem description. --- A child's pogo stick stores energy in a spring with a force constant of 2.50 x 10^4 N/m. At position A (XA= -0.100 m), the spring compression is a maximum and the child is momentarily at rest. At position B (Xb=0) the spring is relaxed and the child is moving u

Thermal Kinetic Energy Problem

As Fig. 8-44 shows, a 4.5 kg block is accelerated by a compressed spring whose spring constant is 640 N/m. After leaving the spring at the spring's relaxed length, the block travels over a horizontal surface, with a coefficient of kinetic friction of 0.25, for a distance of 5.9 m before stopping. (a) What is the increase in

Force Problem

The only force acting on a 2.4 kg body as it moves along the x axis varies as shown in Fig. 7-33 (attached). The velocity of the body at x = 0 is 4.0 m/s. (a) What is the kinetic energy of the body at x = 3.0 m? (b) At what value of x will the body have a kinetic energy of 8.0 J? (c) What is the maximum kinetic energy attai

Reading a Potiential Energy Curve

A single conservation force F(x) acts on a 1.0 kg particle that moves along an x-axis. The potential energy U(x) associated with F(x) is given by: U(x) = -4x e^(-x/4) J, where x is in meters. At x = 5.0m the particle has a kinetic energy of 2.0J. a) What is the mechanical energy of the system? b) Make a plot of U(x) as a

Inelastic collision causes loss of momentum

In physics lab we collided two objects that then both started moving in the same direction. We measured the velocities through two photo gates. We know momentum was lost because the velocities decreased after the collision. What are two physical reasons for the loss of momentum?

Interrupted pendulum

My professor was trying to explain the concept of the interrupted pendulum. I do not understand why most pendulums have the same period and why, when you interrupt a pendulum, it will still reach the same height.

Energy and quantum level

What is the energy of the photon emitted when the electron of a hydrogen atom makes a transition from the quantum level n=3 to the level n=1?

Find the Lagrangian function

Find the Lagrangian function. Please see the attachment. The bottom part of the attachment that got cut off just says "of motion of the particle."

Kinetic energy and rms speed of gas molecules

A cylinder contains a mixture of helium and argon gas in equilibrium at a temperature of 152 degrees Celsius. a) What is the average kinetic energy of each type of molecule (J/molecule)? b) What is the rms speed of each type of molecule? (m/s)

Power

A car maintains a maxiumum speed of 20 meters per second on an uphill road at an angle of 30 degrees. The weight of the car is 10,000 newtons. Determine (a) Power needed to maintain the speed uphill in Kw. (b) Minimum time it will take to accelerate from rest to 30 meters per second on a level road. (c) Max speed it will b

Rotational speed/kinetic enery "A car is designed to get its energy from a rotating flywheel with a radius of 2.20 m and a mass of 499 kg. Before a trip, the flywheel is attached to an electric motor, which brings the flywheel's rotational speed up to 5120 revolutions per minute. Find the kinetic energy stored in the flywheel."

"A car is designed to get its energy from a rotating flywheel with a radius of 2.20 m and a mass of 499 kg. Before a trip, the flywheel is attached to an electric motor, which brings the flywheel's rotational speed up to 5120 revolutions per minute. Find the kinetic energy stored in the flywheel."

Lorentz Force: Desk-Top Sized Proton Accelerator

Your company is designing a desk-top sized proton accelerator, using a 500MN/C superconducting magnet to hold the protons in a circular path. Estimate the maximum kinetic energy that your accelerator can give protons. Express your answer in the conventional particle physics unit of electron-volts, where 1 eV=1.6*10^-19J. For

Springs and Forces

A child's toy consists of a piece of plastic attached to a spring. The spring is compressed against the floor a distance of 2.00 cm, and the toy is released. If the toy has a mass of 90 g and rises to a maximum height of 50.0 cm, estimate the force constant of the spring (in N/m). I need help on which equation/formula to use a