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A photon with a wavelength of \(3.50 \times 10^{-13} \mathrm{~m}\) strikes a deuteron, splitting it into a proton and a neutron. (a) Calculate the kinetic energy released in this interaction. (b) Assuming the two particles share the energy equally, and taking their masses to be \(1.00 \mathrm{u},\) calculate their speeds after the photodisintegration.

Short Answer

Expert verified
The kinetic energy released is \(5.675 \times 10^{-14} \text{ J}\). Each particle moves at approximately \(2.92 \times 10^7 \text{ m/s}\).

Step by step solution

01

Calculate the Energy of the Photon

First, we need to calculate the energy of the incoming photon using the equation \( E = \frac{hc}{\lambda} \), where \( h \) is the Planck's constant \( 6.626 \times 10^{-34} \text{ J} \cdot \text{s} \), \( c \) is the speed of light \( 3 \times 10^8 \text{ m/s} \), and \( \lambda \) is the wavelength \( 3.50 \times 10^{-13} \text{ m} \). Substituting the known values:\[E = \frac{(6.626 \times 10^{-34}) \times (3 \times 10^8)}{3.50 \times 10^{-13}} \]Calculating gives:\[ E \approx 5.675 \times 10^{-14} \text{ J} \]
02

Calculate the Kinetic Energy Released

Assuming the deuteron splits completely into a proton and a neutron without energy loss, the kinetic energy released equals the energy of the incoming photon. Thus, the kinetic energy released is approximately:\[K.E. = 5.675 \times 10^{-14} \text{ J}.\]
03

Convert Mass from Atomic Mass Units to Kilograms

To find the speed of the particles, convert their mass from atomic mass units to kilograms. The mass of one particle \( 1.00 \text{ u} \) is approximately \( 1.66 \times 10^{-27} \text{ kg} \).
04

Calculate the Speed of Particles

The kinetic energy is shared equally, so each particle gets half the energy:\[\text{K.E. per particle} = \frac{5.675 \times 10^{-14}}{2} = 2.8375 \times 10^{-14} \text{ J}.\]Apply the formula for kinetic energy \( K.E. = \frac{1}{2}mv^2 \) and solve for \( v \):\[2.8375 \times 10^{-14} = \frac{1}{2} \times 1.66 \times 10^{-27} \times v^2\]Solving for \( v \), we get:\[ v \approx \sqrt{(2 \times 2.8375 \times 10^{-14}) / 1.66 \times 10^{-27}} \]After calculation:\[ v \approx 2.92 \times 10^7 \text{ m/s} \] for each particle.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Kinetic Energy Calculation
When a photon interacts with a deuteron, the kinetic energy released is a key aspect of the resulting process. In this scenario, the energy of the incoming photon is converted into the kinetic energy of the resulting particles, assuming no energy is lost during the interaction.
Calculating kinetic energy in this context involves understanding that the total energy from the photon is transferred to the kinetic energy of the resulting proton and neutron. To find the kinetic energy, we use:
  • Photon energy formula: this gives the total energy available for conversion into kinetic energy.
The kinetic energy released here is approximately calculated as:\[ K.E. = 5.675 \times 10^{-14} \text{ J} \]This describes the amount of kinetic energy available, perfectly shared between the neutron and the proton after the photon's interaction with the deuteron.
Photon Energy Formula
The photon energy can be detailed using the equation:\[ E = \frac{hc}{\lambda} \]where \( h \) is the Planck's constant \( 6.626 \times 10^{-34} \text{ J} \cdot \text{s} \), \( c \) is the speed of light \( 3 \times 10^8 \text{ m/s} \), and \( \lambda \) is the photon's wavelength. This equation comes from the understanding that a photon carries quantized energy, dependent on its wavelength.
This direct calculation helps us determine the energy delivered by the photon involved in the reaction. Given a wavelength of \( 3.50 \times 10^{-13} \text{ m} \), substituting these values gives the energy:\[ E \approx 5.675 \times 10^{-14} \text{ J} \]This equation is fundamental in physics, underscoring the relationship between a photon's energy and its wavelength.
Particle Speed Calculation
To determine how fast the particles (proton and neutron) move after the deuteron splits, we use the concept of kinetic energy sharing. The kinetic energy formula is:\[ K.E. = \frac{1}{2}mv^2 \]where \( m \) is the mass, and \( v \) is the speed we need to calculate. Given that both particles equally share the total kinetic energy, each receives:\[ \text{K.E. per particle} = \frac{5.675 \times 10^{-14}}{2} = 2.8375 \times 10^{-14} \text{ J} \]Plugging this energy into the kinetic energy formula allows us to solve for \( v \), the speed of each particle. Rearranging terms and solving gives:\[ v \approx \sqrt{\frac{(2 \times 2.8375 \times 10^{-14})}{1.66 \times 10^{-27}}} \approx 2.92 \times 10^7 \text{ m/s} \]This result tells us the velocity at which each resulting particle travels, providing insight into the dynamics of particle interactions.
Atomic Mass Unit Conversion
Converting atomic mass units (amu) to kilograms is crucial when calculating the speed of particles. One atomic mass unit (\( 1 \text{ u} \)) is approximately equal to \( 1.66 \times 10^{-27} \text{ kg} \). This conversion is necessary because the equations used in kinetic energy calculations require mass in kilograms.
  • Ensure accuracy by consistently using this conversion factor in calculations involving atomic particles.
In our scenario, both the proton and the neutron are assumed to have a mass of \( 1.00 \text{ u} \), translating to a mass of approximately \( 1.66 \times 10^{-27} \text{ kg} \) each.
Knowing their mass in kilograms allows us to use the kinetic energy formula to accurately determine their speeds. Properly understanding unit conversions is foundational to solving physics problems involving atomic particles.

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Most popular questions from this chapter

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