7 Someone is trying to balance a (110cm) plank with certain forces. a) Calculate the moment of the 60N force (about O), then name its type. b) Calculate the moment of the 30N force (about O), then name its type c) Will the plank balance? If not, which way will it tip? d) What extra force would be needed at (B) to balance the plank?

Which of these statements is true? a. quarks pair with leptons to form protons and neutrons. b. quarks pair with bosons to form photons. c. quarks pair with photons to form protons and neutrons. d. quarks pair with other quarks to form protons and neutrons. e. quarks pair with electrons to form protons.

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?

Which of the following are appropriate acceleration units?