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A bare helium nucleus consists of two protons and two neutrons and has a mass of 6.64 × 10–²⁷ kg.

A. Calculate its kinetic energy in joules at 2.00% of the speed of light. Use the non-relativistic formula.
B. What is this in electron volts?
C. What voltage would be needed to obtain this energy?

1 Answer

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Final answer:

The kinetic energy of a bare helium nucleus at 2.00% of the speed of light is 5.312 × 10–¹² J. This is equivalent to 3.320 × 10⁷ eV. To obtain this energy, a voltage of 1.327 × 10^–¹² V is needed.

Step-by-step explanation:

To calculate the kinetic energy of a bare helium nucleus at 2.00% of the speed of light, we can use the non-relativistic formula for kinetic energy: KE = (1/2)mv^2.

Given that the mass of the helium nucleus is 6.64 × 10–²⁷ kg and the velocity is 2.00% of the speed of light, we can calculate the kinetic energy:

KE = (1/2)(6.64 × 10–²⁷ kg)(2.00%c)^2

where c is the speed of light (3.00 × 10^8 m/s).

Substituting the values, we get:

KE = (1/2)(6.64 × 10–²⁷ kg)(0.02c)^2 = 5.312 × 10–¹² J

To convert this energy to electron volts (eV), we can use the conversion factor: 1 eV = 1.602 × 10–¹⁹ J. Therefore, the kinetic energy in electron volts is:

KE (eV) = (5.312 × 10–¹² J)/(1.602 × 10–¹⁹ J/eV) = 3.320 × 10⁷ eV

To calculate the voltage needed to obtain this energy, we can use the equation: V = KE/q, where V is the voltage, KE is the kinetic energy, and q is the charge of the helium nucleus (2 times the elementary charge: 2e).

Substituting the values, we get:

V = (5.312 × 10–¹² J)/(2e) = 1.327 × 10^–¹² V

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