What happens when a substance undergoes a physical change

What type of electromagnetic wave is used in security pens? a. x-rays c. microwaves b. visible light d. ultraviolet radiation select the best answer from the choices provided

Ms.hidalgo opens the door to her classroom. her classroom is 60 degrees and the air outside is 80. predict what will happen using your knowledge of how heat flows.

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)