78. A particle moves along the x- axis. The velocity of the particle at time tis given by 4vt()=3 t +1 . If the position of the particle is x=1when t=2, what is the position of the particle when t=4? (A) 0.617 (B) 0.647 (C) 1.353 (D) 5.713

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?

Aswimming pool whose volume is 10 comma 000 gal contains water that is 0.01% chlorine. starting at tequals0, city water containing 0.003% chlorine is pumped into the pool at a rate of 5 gal/min. the pool water flows out at the same rate. what is the percentage of chlorine in the pool after 1 hour? when will the pool water be 0.006% chlorine?

How does the strength of the electrostatic force between an electron and a proton compare to the strength of the gravitational force between them?