Question

Which of the following quantities related to an electron has a finite upper limit?
(a) Mass
(b) Momentum
(c) Speed
(d) Kinetic energy

Answer 1

Speed is your answer ......

Answer 2

The answer is (c) speed.

Explanation:

• Let us consider that the electron has a very high-speed v. It will have the mass $\mathrm{m}=\mathrm{mol}-\mathrm{v} 2 \mathrm{c} 2=\mathrm{ymo}$
• It will have the momentum, $\mathrm{p}=\mathrm{ymov}=\mathrm{mv}=\mathrm{mov} 1-\mathrm{v} 2 \mathrm{c} 2$ kinetic energy, $\mathrm{k}=12 \mathrm{ymov} 2=12 \mathrm{mv} 2=12 \mathrm{mov} 21-\mathrm{v} 2 \mathrm{c} 2 \mathrm{y}=\mathrm{c}_{1} \mathrm{x}=11-\mathrm{v} 2 \mathrm{c} 2 \mathrm{at} \mathrm{v}=11-\mathrm{c} 2 \mathrm{c} 2=\infty$

        $\Rightarrow \text { when } y=c, m=k=0=-\infty$

• Consequently, for v, there will be an upper bound to be continually less than c but there will be no upper limits for the electron’s momentum, mass and kinetic energy.