The most massive Shinkansen bullet trains are the series-200 trains. This type of train also has one of the highest operating speeds: 76.4 m/s. If a series-200 train has a maximum kinetic energy of 2.78x 10 to the 9J, what is its mass?

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?