Question

The rest mass of an electron is 9.11x10-31 kg. What is the mass when travelling with a speed of 0.8 c​

Answer 1

Answer:

$14.576 \times 10⁻¹⁴ J$

Explanation:

Rest mass of electron,

m₀ = 9.11 × 10⁻³¹ Kg

speed of electron,

v = 0.8c

we know, total energy = mc²

= m₈c²/(1 - v²/c²)

T.E = (9.11 × 10⁻³¹)*(3 * 10⁸)²/(1-0.64)

= 9.11 * 10⁻¹⁵ * 9/0.36

T.E = 22.775 * 10⁻¹⁴ J

now, Kinetic energy = 22.775 * 10⁻¹⁴ - m₉c²

= 22.775 * 10⁻¹⁴ - 9.11 * 10⁻³¹ (3* 10⁸)²

= 14.576 * 10⁻¹⁴ J