29. Two friends are pushing a crate in the same direction. One friend is pushing with a force of 250 N while the other friend is pushing with a force of 180 N. The surface they are pushing on
has a friction force of 20 N in the opposite direction. What is the net force acting on the crate?
PLEASE PLEASE HELP!

Unpolarized light of intensity so passes through two sheets of polarizing material whose transmission axes make an angle of 60∘ with each other as shown in the figure. what is the intensity of the transmitted beam, st?

(a) calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 10.0 g. silver has 47 electrons per atom, and its molar mass is 107.87 g/mol. (b) imagine adding electrons to the pin until the negative charge has the very large value 1.00 mc. how many electrons are added for every 109 electrons already present

Name two kinds of practical electric pumps.