Pure sodium metal placed in water will spark and ignite, as well as form bubbles and gas. what are the signs that this is a chemical reaction? check all that apply.

heat is produced.

light is produced.

heat is absorbed.

bubbles appear.

a precipitate forms.

the color changes.

Which statement best describes how private industry decides where to spend the money on research and development

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

An charge with mass m and charge q is emitted from the origin, (x,y)=(0,0). a large, flat screen is located at x=l. there is a target on the screen at y position y(h), where y(h) > 0. in this problem, you will examine two different ways that the charge might hit the target. ignore gravity in this problem. 1.assume that the charge is emitted with velocity v(0) in the positive x direction. between the origin and the screen, the charge travels through a constant electric field pointing in the positive y direction. what should the magnitude e of the electric field be if the charge is to hit the target on the screen? express your answer in terms of m, q, y(h), v(0), and l. 2.now assume that the charge is emitted with velocity v(0) in the positive y direction. between the origin and the screen, the charge travels through a constant electric field pointing in the positive x direction. what should the magnitude e of the electric field be if the charge is to hit the target on the screen? express your answer in terms of m, q, y(h), v(0), and l.