A rock is tied to a string and swung inner circle at a constant speed of 4 m/s. if the rock feels a centripetal acceleration of 5 m/s^2. what is the length of the string? A. 0.8 m
B. 1 m
C. 1.25 m
D. 3.2 m

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?