Astep-up transformer connected to a 110-v line is used to supply a hydrogen-gas discharge tube with 5.0 kv (rms). the tube dissipates 140 w of power. (a) what is the ratio of the number of turns in the secondary winding to the number of turns in the primary winding? (b) what are the rms currents in the primary and secondary windings? (c) what is the effective resistance seen by the 110-v source?

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?

The temperature in gavin's oven is a sinusoidal function of time. gavin sets his oven so that it has a maximum temperature of 280°f and a minimum temperature of 240°. once the temperature hits 280°, it takes 20 minutes before it is 280° again. gavin's cake needs to be in the oven for 30 minutes at temperatures at or above 270°. he puts the cake into the oven when it is at 260° and rising. how long will gavin need to leave the cake in the oven? (round your answer to the nearest minute.)

What is the role of the water cycle in maintaining freshwater levels in lake and rivers?