Question

The brightest, hottest, an
ne brightest, hottest, and most massive stars are the brilliant blue stars designated as spectral class O. If a class O star with a mass of 3.38 x 1031 kg has a kinetic
energy of 1.10 x 1042 J, what is its speed? Express your answer in km/s (a typical
unit for describing the speed of stars).

Answer 1

The speed of the star is 255 km/s

Explanation:

The kinetic energy of a body is the energy possessed by the body due to its motion. Mathematically:

$KE=\frac{1}{2}mv^2$

where

m is the mass of the object

v is its speed

For the star in this problem, we have:

$m=3.38\cdot 10^{31} kg$ is the mass

$KE=1.10\cdot 10^{42} J$ is the kinetic energy

Therefore, the speed of the star is:

$v=\sqrt{\frac{2KE}{m}}=\sqrt{\frac{2(1.10\cdot 10^{42})}{3.38\cdot 10^{31}}}=2.55\cdot 10^5 m/s$

Which corresponds to 255 km/s

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Answer 2

This question involves the concepts of kinetic energy and the velocity.

The velocity of the star is "255 km/s".

The kinetic energy of the star is given by the following formula:

$K.E =\frac{1}{2}mv^2\\\\v=\sqrt{\frac{2K.E}{m}}$

where,

v = velocity = ?

K.E = kinetic energy = 1.1 x 10⁴² J

m = mass = 3.38 x 10³¹ kg

Therefore,

$v=\sqrt{\frac{2(1.1\ x\ 10^{42}\ J)}{3.38\ x\ 10^{31}\ kg}}$

v = 2.55 x 10⁵ m/s = 255 km/s

Learn more about kinetic energy here:

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