# Physics

Calculate the kinetic energy that the earth has because of its rotation about its own axis. Assume that the earth is a uniform sphere and that its path around the sun is circular. For comparison, the total energy used in the United States in one year is about 9.33 109 J.

Calculate the kinetic energy that the earth has because of its motion around the sun.

In either case, the trick is to calculate the moment of inertial.
In the first case, the moment of inertia of a solid sphere rotating about its axis.

In the second case, MassEarth*distancefromSun^2.

Then, KE= 1/2 I* radiusofrotation^2

Please check. The answer i came up with is wrong.

a.
rotational KE = 1/2(Iw^2)
=1/2(2/5mr^2)w^2
=(7.63048x10^30kg*m)(39.4384/2.49x10^-13)
= 1.210 x 10^18

1. 👍
2. 👎
3. 👁

## Similar Questions

1. ### Physics: Rotational Motion

A 0.005kg bullet travelling horizontally with a speed of 1000m/s enters an 18kg door, embedding itself 10cm from the side opposite the hinges as in figure. The 1m wide door is free to swing on the hinges. a) Before it hits the

2. ### Physics

A student sits on a rotating stool holding two 3.4-kg objects. When his arms are extended horizontally, the objects are 1.0 m from the axis of rotation and he rotates with an angular speed of 0.75 rad/s. The moment of inertia of

3. ### PHYSICS

I AM SORRY I JUST HAVE ONE OF THE MOST HORRIBLE TEACHERS, AND I AM TEACHING MYSELF FOR I GET NOTHING IN CLASS. On an old-fashioned rotating piano stool, a woman sits holding a pair of dumbbells at a distance of 0.565m from the

4. ### Physics Question......many thanks

A projectile is shot directly away from Earth's surface. Neglect the rotation of Earth. (a) As a multiple of Earth's radius RE, what is the radial distance a projectile reaches if its initial speed is one-fifth of the escape speed

1. ### 6th math

Every 24 hours, Earth makes a full rotation around its axis. Earth's speed of rotation at the equator is 1,670 km per hour. What is the circumference of Earth's equator?

2. ### Physics

Calculate the kinetic energy that the earth has because of (a) its rotation about its own axis and (b) its motion around the sun. Assume that the earth is a uniform sphere and that its path around the sun is circular. For

3. ### Physics

Which of the following is the correct equation for Στ for the given rotation axis? All rotation axes lie on the x axis and torques that would cause a counterclockwise rotation are positive.

4. ### Science

Luis wanted to create a clay model of earth and the sun. To show how Earth rotates, Luis wants to use a toothpick to represent Earth's axis of rotation. Where should Luis place the toothpick? A. Horizontally through Earth in the

1. ### physics

Determine the torques about the axis of rotation P produced by each of the four forces shown in the figure (Figure 1). All forces have magnitudes of 120 N and are exerted a distance of 2.0 m from P on some unshown object O.