Question

Celebration of Knowledge 2/21/2020 ber balloon gains excess electrons when a strange physics professor rubs the balloon in is hair. If the professor then touches the balloon to a wall, and it sticks, the balloon will be inducing a charge on the wall that is equal and opposite to its charge. This was demonstrated in class! (a) (5 points) Draw and label the balloon while it is stuck to the wall. Be sure to indicate the charges that are on both the balloon and the wall. (b) (15 points) Determine an expression for the coefficient of static friction between the bal- loon and the wall. Recall: f.=uN. Your expression should be in terms of m, g, k, q, and d; where: mis mass, g is the constant associated with the acceleration due to gravity, q is charge, and d is the distance between the balloon and the wall. (c) (5 points) If us = 0.81, m = 7.5g and q = 7nC, determine the actual distane between the balloon and the wall.

Answer 1

+ + EL + + Solution: (a) q = - ve charge on " balloon = the chare Induce on ballon (2,1 = 12,1 = 121 (6) Electric force between Ne balloon and wall is atractive! fr = MgN t f. = K 2 Fe = K2 from condition of equillibrium N=fe f = force of friction = Cofficient of stater friction and ing=f mga MsN = us ke Чут 6% K= 1 = Constant da distance between balloon and wall. (c) If 4 = 0.81 m = 7.5g and q = 7ne m=0.0075kg 2-7x10c Firmez. O us = mgde de Mke kiz

d- [10.81) (9x109) (7x159) 2. 10.0075) (10) d = [357.21x10-9 - [4762.8 X10-9 10.075 = 1476.28x108 Id=27.8x14m distance between balloon and wall.