Explain why machines are never 100% efficient.

Determine the critical height h of the water level that causes the concrete gravity dam to be on the verge of tipping over due to water pressure. the density of concrete is ρc = 2.40 mg/m3. suppose that hd = 38 m. hint: work the problem using a 1-m width of the dam.

Place several e-field sensors at a few points on different equipotential lines, and look at the relationship between the electric field and the equipotential lines. which statement is true? 1-at any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of higher voltages. 2-at any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of lower voltages. 3-at any point, the electric field is parallel to the equipotential line at that point.

How is the acceleration of an object in uniform circular motion constant? a - in magnitude only b - in direction only c - in both magnitude and direction d - in magnitude, direction & orientation