How Do You Calculate the Momentum of a Proton in MeV/c?

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The discussion focuses on calculating the momentum of a proton in MeV/c, emphasizing the relationship between energy, momentum, and velocity. The electron-volt (eV) is defined as a unit of energy, with 1 MeV equating to 1.602 x 10^-13 J. Momentum is expressed in MeV/c, where c represents the speed of light, and the mass of a proton is given as 938.3 MeV/c². Participants discuss the need to understand the units of momentum and how to approach the problem, with hints provided to guide the calculation. Understanding the conversion between energy and momentum units is crucial for solving the problem.
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The electron-volt, eV, is a unit of energy (1 eV = 1.602 10^-19 J, 1 MeV = 1.602 x 10^-13 J). Since the unit of momentum is an energy unit divided by a velocity unit, nuclear physicists usually specify momenta of nuclei in units of MeV/c, where c is the speed of light (c = 2.998 108 m/s). In the same units, the mass of a proton (1.673 · 10^−27 kg) is given as 938.3 MeV/c2. If a proton moves with a speed of 18,646 km/s, what is its momentum in units of MeV/c?
The attempt at a solution

I know the rule of the forum is I have to attempt the problem before someone can help me. But, honestly I don't know how to initiate this problem. I have tried but failed.

It will be appreciated if someone can at least show me the procedure if not the answer.
 
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What are the units of pc, where p is the momentum of the proton?
 
What is pc? I don't see any pc in the given problem :/
 
bump :/
 
J.live said:
What is pc? I don't see any pc in the given problem :/

There is a pc in the problem, you just don't see it yet. Determine the units of this quantity and you should have a strong hint about how to get the answer you're looking for.
 
Hint: 1 MeV/c = 1.602x10-13 J/(3x108 m/s)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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