Earth has a mass of 5.98 1024 kg and a radius of 6.38 106 m. Assume it is a uniform solid sphere. The distance of Earth from the Sun is 1.50 1011 m. (Assume Earth completes a single rotation in 24.0 hours and orbits the Sun once every 365 Earth days.) (a) What is the rotational kinetic energy of Earth on its axis

Explanation

Rotational kinetic energy of the earth = 1/2 Iω²

where I is moment of inertia of the earth and ω is angular velocity .

I = 2/5 m R² , m is mass and R is radius of the earth .

I = 2/5 x 5.98 x 10²⁴ x ( 6.38 x 10⁶ )²

=97.36 x 10³⁶

ω = 1 / T

T = 24 x 60 x 60 = 86400 s

ω = 1 / 86400

= 11.57 x 10⁻⁶ rad / s

Rotational Kinetic energy = 1/2 Iω²

= .5 x 97.36 x 10³⁶ x (11.57 x 10⁻⁶ )²

= 6516.54 x 10²⁴ J