What is a density dependent limiting factor?

Excuse ! extra points plus ! super desperate ! the position of an object does not move relative to a reference point. relative to the reference point the object _. a.) is not moving. b.) is moving.

A26 cm object is 18 cm in front of a plane mirror. a ray of light strikes the object and is reflected off the mirror at a 42-degree angle. what is the angle of reflection? degrees what type of image is formed? what is the size of the image? cm

Given the position vector of the particle r(t)=(t+1)i+(t^2−1)j+2t k, find the particle's velocity and acceleration vectors at t=1