Mike and Tim are outside with a wagon. Tim weighs 311 Newtons (70lbs) and gets in the wagon and Mike, who weighs 50 Newtons (50lbs), pulls it. As Mike pulls it, he accelerates until reaching a constant velocity. After stopping, Mike and Tim switch places. Tim now pulls Mike in the wagon, accelerating from a stop to a constant velocity . Now, Tim may be bigger than Mike, but Mike has been working out and is just as strong as Tim, so the force that Tim uses to pull the wagon is the same force that Mike used. Both pull with the exact same amount of force. Who was riding in the wagon when it had the greatest acceleration during start up? Why? Use Newton’s second law to explain. Now Sara comes along, and she is the exact same size as Mike. However, she is even stronger than Mike! When she pulls Mike in the wagon, she pulls with a greater force than when Mike pulls her. Now who is in the wagon when it has the greatest acceleration? Explain, using Newton’s second law.

Experiments in environmental toxicology can sometimes be manipulative experiments in which the researcher actively chooses and manipulates the independent variable. in hunt's study, for example, dosages of bpa were manipulated and the effects were measured. in manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable. in other cases, researchers use natural experiments in which the dependent variable (typically a measure of organism health) is measured under differing contexts that are not manipulated. say, for example, that an accidental chemical spill contaminates five ponds. to determine the possible effects of the toxic chemical on frogs, a researcher could compare the hatching rate of frog eggs laid in those five ponds to the hatching rate of eggs laid in five uncontaminated ponds nearby. this would be an example of a natural experiment because concentrations of the toxic chemical in the ponds were not controlled by the experimenter, but rather resulted from the chemical spill. drag type of experiment on the left to the example of experiment on the right. blood concentrations of bpa in college students are compared to their recent manipulative consumption of canned food items 2. the feeding behavior of fish in streams that receive acidic runoff from strip mines is compared to the feeding behavior of fish in unaffected streams. the deformity rate in baby birds from nests in pesticide-sprayed fields is compared to the deformity rate in birds from nests in unsprayed fields 4 tumor development is compared in mice exposed to five dosages of a known carcinogen in the laboratory foraging activity levels are compared in tadpoles exposed to four concentrations of toxic metals in the laboratory. growth of corn plants is compared in field plots sprayed with three different dosage: s of weed killer 7 bpa concentrations in the urine of people with diabetes are compared to bpa concentrations in the urine of people without diabetes - natural; manipulative

Lola needs to sign 6 invitations. using stopwatch that measures time to tenths of a second, it takes lola 5.3 seconds to sign her full name. going by the accuracy of the stopwatch, which is the most accurate determination for the number of minutes lola needs to sign all 96 invitations

Drag the tiles to the correct boxes to complete the pairs. match the nitrogenous base of dna with its complement.