## Kinetic Energy Problem

$\Delta p \Delta x\geq \frac{h}{4\pi }$

Samantha Lee 1A
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### Kinetic Energy Problem

Hello - In one of the Audio-visual videos, there was a problem on how to calculate the kinetic energy using the Heisenberg Uncertainty equation. I was confused on how to address a problem like this in the future. Any advice?

Chem_Mod
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### Re: Kinetic Energy Problem

Hi, can you please post the specific question you are referring to?

Aaina 2D
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Joined: Wed Sep 30, 2020 9:41 pm

### Re: Kinetic Energy Problem

Well in general, to calculate the kinetic energy, you would need the values of mass and velocity. The Heisenberg indeterminacy equation itself is delta p x delta x >= h/4pi. Once you are able to find delta p, you can use the equation for momentum indeterminacy: delta p = m x delta v. After plugging in values, you can solve for v, velocity. This way, you'll have all values needed to calculate the kinetic energy - velocity and mass.

Note: the mass is usually given to you.

Hope this helps!

Pranav Daggubati 3C
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### Re: Kinetic Energy Problem

Heisenberg's Uncertainty Equation states that change in momentum and change in position are inversely related with a constant of proportionality of planck's constant divided by 4 pi: $\Delta p \cdot \Delta x \geq \frac{h}{4\pi}$. In any given example, you should be able to extrapolate the mass of a particle from the periodic table and few dimensional analysis calculations. Then, using $\Delta p = m \Delta v$ for the momentum, you find the velocity of the particle. You use the mass and the velocity to then find the kinetic energy of the particle as we know that the kinetic energy is defined by$K.E. = \frac{1}{2}mv^{2}$.

Jasmine Yi 1G
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Joined: Wed Sep 30, 2020 9:37 pm

### Re: Kinetic Energy Problem

In general, the Uncertainty Equation will give you delta momentum, which will give you delta velocity. You can use the delta velocity to find kinetic energy because kinetic energy = 0.5(m)(v^2). Remembering this general pathway can help in figuring out what direction to go. Hope this helps!