A motorboat maintained a constant speed of 15 miles per hour relative to the water in going 12 miles upstream and then returning. The total time for the trip was 2.5 hours. Use this information to find the speed of the current.
The speed of the current is
miles per hour.

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.

J. j. thomson’s experiment disproved the theory that an atom

Which statement is true? a) the work done to lift an object 6 meters is greater than the gravitational potential energy it gains. b) the work required to push an object is less than the work required to pull an object the same distance. c) the work required to raise an object to a height is equal to the gravitational potential energy the object gains. d) the work done against gravity to lift an object straight up is greater than the work required to roll it up a ramp.