How much work does a crane do to lift a 144 kg crate up 34 m in the air?

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Sort the images based on whether there's a force of attraction or repulsion between the magnets shown. attraction repulsion

Auniform crate c with mass mc is being transported to the left by a forklift with a constant speed v1. what is the magnitude of the angular momentum of the crate about point a, that is, the point of contact between the front tire of the forklift and the ground