Asquare is cut out of a copper sheet. two straight scratches on the surface of the square intersect forming an angle theta. the square is heated uniformly. as a result, the angle between the scratches? a) increasesb) decreasesc) stays the samed) depends on whether theta is obtuse or acute

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

If the specific heat of a metal is 0.850 j/g °c, what is its atomic weight?

What is an electric motor? explain its operation. 2-3 sentence