18. a dam generates electricity from water flowing downhill and is an example of how systems… a. violate the 2nd law of thermodynamics b. take advantage of energy flow from low to high c. violate the 3rd law of thermodynamics d. take advantage of energy flow from high to low

When a 5.0kg cart undergoes a 2.2m/s increase in speed, what is the impulse of the cart

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?