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An electron and a proton have their masses in the ratio 1:1840. What will be the ratio of their kinetic energy if they have equal momentum?<
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Answers ( )
Answer:
1840:1
Explanation:
If m is the mass of the electron, and 1840m is the mass of the proton, then:
p₁ = p₂
m₁v₁ = m₂v₂
m v₁ = 1840m v₂
v₁ = 1840 v₂
The kinetic energy of the electron is:
KE₁ = ½ m₁ v₁²
KE₁ = ½ m (1840 v)²
KE₁ = 1692800 mv²
The kinetic energy of the proton is:
KE₂ = ½ m₂ v₂²
KE₂ = ½ (1840m) v₂²
KE₂ = 920 mv²
The ratio of the kinetic energies is:
KE₁ / KE₂
(1692800 mv²) / (920 mv²)
1840:1