My extra credit homework. plzzz help?

Question

1. Two blocks each of mass m are fastened to the top of an elevator as in the figure below. The elevator has an upward acceleration a. The strings have negligible mass.

(a) Find the tensions T1 and T2 in the upper and lower strings in terms of m, a, and g.

(b) Compare the two tensions and determine which string would break first if a is made sufficient large.

(c) What are the tensions if the elevator cable breaks?

2. An inquisitive boy rides on a roller coaster sitting on a bathroom scale.The bottom of the seat in the roller-coaster car is in a plane parallel to the track. The seat has a perpendicular back and a seat belt that fits around the boy's chest in a plane parallel to the bottom of the seat. The boy lifts his feet from the floor so that the scale reads his weight, 170 lb, when the car is horizontal. At 1 point during the ride, the car zooms w/ negligible friction down a straight slope inclined at 14° below the horizontal. What does the scale read at tht point(in lbs)

Answer 1

wow what grade is this in?

Answer 2

I'll just give you some hints about how to do it since it's homework.

Since I don't have the diagram I'll assume that there is one block hanging from the elevator ceiling by a string and another block hanging from the first block by another string.

Now, look at the bottom mass first.  You know it is accelerating upward with acceleration a.  Think of all the forces acting on the bottom mass and put them into Newton's second law: Fnet = ma.  This will give you an equation involving T1, T2.

Now do the same thing with the other mass.  You will get another equation involving T1 and T2.

Now solve the two equations for T1 and T2 in terms of the other quantities.