A55-kg hiker starts at an elevation of 1600 m and climbs to the top of a 3100-m peak. (a) what is the hiker's change in potential energy? (b) what is the minimum work required of the hiker? (c) can the actual work done be more than this? explain why.

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.

Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. the researchers grew one type of bacteria in twenty-four identical covered petri dishes. then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. they left the remaining six petri dishes closed as a control group. when the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. the researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. which statement best explains why the researchers’ conclusion was not justified? the experiment tested too many variables. the control group was not treated the same as the experimental group. the sample size of twenty-four petri dishes is not large enough. the single type of bacteria is not adequate to make any conclusions.

Which statements did both aristotle and ptolemy assume? check all that apply.