What is the change in angular momentum of a planet with radius R if an asteroid mass m and speed v hits the equator at an angle from the west, 40 degrees from the radial direction?

Angular momentum about the spin axis is conserved. The planet with added asteroid will gain angular momentum equal to that of the asteroid before collision. You have not said what the initial planet mass or angular momentum was.

Angular momentum change = m*v*R*sin40

It can be either an increase ior decrease depending upon the direction the planet was originally spinning.

The planet has mass M and is spinning in a counterclockwise direction. I know the asteroid will increase the momentum of the planet, so the total change in angular momentum is equal to positive. m*v*R*sin(40) ?

To determine the change in angular momentum of a planet when an asteroid hits it, we need to calculate the initial and final angular momentum, and then find the difference between them.

1. Determine the initial angular momentum:
The formula for angular momentum is given by L = I * ω, where L is the angular momentum, I is the moment of inertia, and ω is the angular velocity. In this case, we are interested in the change in angular momentum, so we can disregard the specific values and focus on the change itself.

2. Calculate the final angular momentum:
If the asteroid hits the planet at an angle, the initial angular momentum will be transferred to the planet. Since the asteroid hits the equator, we can assume that the planet's rotation axis is aligned with the normal to the equatorial plane. Therefore, the moment of inertia of the planet will remain constant, and the only change will be in the angular velocity.

3. Determine the change in angular velocity:
To find the change in angular velocity, we can use the conservation of angular momentum. The initial angular momentum of the asteroid is given by L_initial = m * r * v_initial, where m is the mass of the asteroid, r is the distance from the planet's axis to the point of impact, and v_initial is the initial velocity of the asteroid. The final angular momentum of the planet is given by L_final = I * ω_final.

4. Calculate the change in angular momentum:
The change in angular momentum is the difference between the final and initial angular momentum, which can be expressed as ΔL = L_final - L_initial.

By following these steps, you can calculate the change in angular momentum of the planet when the asteroid hits it. Make sure to plug in the specific values for the mass, speed, angle, and radius in order to obtain a numerical answer.