On a day when the temperature is 20°C, a concrete walk is poured in such a way that its end are unable to move. (A) what is the stress in the cement when its temperature is 50°C on a hot, sunny day? (B) Does the concrete fracture? Take Young's modulus for concrete to be 7.00 ×10^9 N/m^2

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.