Join the IDNLearn.com community and start finding the answers you need today. Get accurate and timely answers to your queries from our extensive network of experienced professionals.

A) Calculate the torque required to accelerate the Earth in 7 days from rest to its present angular speed about its axis. (b) Calculate the energy required. (c) Calculate the average power required.

Sagot :

Answer:

A) 1.3013476 × 10²⁸ N·m

b) 2.8618128 × 10²⁹ J

c) 4.73183333 × 10²³ W

Explanation:

The mass of the Earth, M = 5.972 × 10²⁴ kg

The radius of the Earth, R = 6,371 km

The angular speed of the Earth, ω = 2·π/(24 hr) = 7.27220522 × 10⁻⁵ rad/s

The shape of the Earth ≈ Spherical

The moment of inertia of a sphere, I = (2/5)·M·R²

The angular acceleration of the Earth in 7 days from rest its present angular speed, ω, is given as follows;

 α = 7.27220522 × 10⁻⁵ rad/s/((7 × 24 × 60 × 60) s) = 1.2024149 × 10⁻¹⁰ rad/s²  

Torque, τ = I × α

∴ τ = (2/5) × 5.972 × 10²⁴ × 6,731,000² × 1.2024149 × 10⁻¹⁰ = 1.3013476 × 10²⁸

The torque required, τ = 1.3013476 × 10²⁸ N·m

b) The energy required, [tex]K.E. _{(Rotational)}[/tex] = 1/2 × I × ω²

∴  [tex]K.E. _{(Rotational)}[/tex] = (1/2) × (2/5) × 5.972 × 10²⁴ × 6,731,000² × (7.27220522 × 10⁻⁵ rad/s)²

The energy required, [tex]K.E. _{(Rotational)}[/tex] = 2.8618128 × 10²⁹ J

c) Power = Energy/Time

Therefore, the average power required, P = [tex]K.E. _{(Rotational)}[/tex]/Time

∴ P = 2.8618128 × 10²⁹ J/(7 × 24 × 60 × 60) s) = 4.73183333 × 10²³ Watts

The average power required, P = 4.73183333 × 10²³ Watts.