Ineed a equation for a problem in using a pulling force a mass a coefficient of static friction a coefficient of kinetic friction and solving for the frictional force

Why is alternating current more effective at long–distance travel than direct current? a. the power lines are made out of conductors. b. transformers increase or decrease voltage as needed. c. the ac generator is more efficient. d. ac has lower voltage than dc.

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?

The path of a satellite orbiting the earth causes it to pass directly over two tracking stations a and b, which are 51 miles apart. when the satellite is on one side of the two stations, the angles of elevation at a and b are measured to be 87 degrees and 84 degrees, respectively. (a) how far is the satellite from station a? (b) how high is the satellite above the ground?