Does altitude has an effect on weight? HELP​

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

What are the dimensions of the cross section that passes through the points a, f, g, and d?

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.