Which of the following is a characteristic of ALL chemical changes? A. a phase change occurs B. light is emitted C. a new material is formed d. some mass is converted to energy

Ireally need this answer sombody fast fast

You are given a vector a = 125i and an unknown vector b that is perpendicular to a. the cross-product of these two vectors is a × b = 98k. what is the y-component of vector b?

Two carts, one of mass 2m and one of mass m, approach each other with the same speed, v. when the carts collide, they hook together. assume that positive momentum is to the right. which graph best represents the momentum of both carts over time, before and after the collision?