The four limitations are
1.It's often impossible to repeat trials on the same subjects.
2-Subjects may report an inaccurate medical history.
3-It can be difficult to control all possible variables.
4-It's impossible to come up with testable scientific questions for human subjects.
Research involving human beings is ultimately necessary for improvements in human health and welfare. Any results about healthy physiology, illness causes, treatment effectiveness, learning, or behavior must be verified by carefully controlled investigations involving human participants. Sadly, not all human research have been valid and beneficial. It is possible to harm people in the name of research. The most well-known instances happened in Nazi Germany. Investigations conducted after the war found several crimes, including experiments in which participants were submerged in extremely cold water to determine how long it would take them to pass away from hypothermia.
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Answer:
Water pollution is one of the most common type of pollution that leads to the deterioration of the water quality mainly due to the man-made interference. Direct and indirect pollution are two of its types. Direct pollution as the term suggests refers to the direct flow of pollutants in the water in contrast to the indirect pollution that accounts for the transport of pollutants eventually to the water body.
Explanation:
Direct pollution is characterized by the release of toxic fluid directly in the water body. The main source of this type of pollution are the toxic pollutants from the large factories. Some of the other sources includes solid waste from the household activities and waste from agricultural practice like fertilizers, and the waste generated by the waste water treatment plant.
Note 1: Balanced forces do not cause alterization motion or movement. This is because of the fact that balanced forces are equal in size and in opposite directions. Consequently, this leads to cancellation and ultimately no movement.The net force for balancing forces is always 0.
Think of it this way: Take your right hand and left hand. Press them together; palm-to palm and five fingers to five fingers. Now apply equal amount of pressure (your force) as you push them in opposite directions (left hand left direction right hand right direction) Does any change in movement occur?
Note 2: Unbalanced forces are the forces that cause change in movement and motion. When two unbalanced forces are exerted in opposite directions, the overall force (or net force) is the difference between the two forces and the direction is in favor for the larger force.
Think of it this way. Repeat the exercise I shown you in Note 1, but this time, make apply more force in comparison to the other hand. Your right/left hand's force overpowers the weaker force of the opposite hand. The direction is in favor to your right/left hand (since they obtain the bigger force) as your hands move to the right or left side. This is an example of unbalanced forces at play.
Q22: The two forces on the left and right side are balanced given that their force is equal in size and they are in opposite directions. The two forces northwards and southwards are unbalanced forces since they are not equal in size but are opposite in direction. Recall in note 2 when I given the formula to find the net force for unbalanced forces. Its the difference (subtraction) between the bigger force and smaller force. 5 - 2 = 3. Therefore the net force for question 22 is 3.The direction is in the bigger force's direction, therefore southwards.
Q24: Is a balanced force. Therefore the net force is 0. I don't think there is technically any direction per say.
Answer:
brine flies prefer warm temperatures to breed in, more brine flies means more food for the brine shrimp, so brine shrimp will be able to breed more as there's more food. and vice versa- in colder temperatures there would be less breeding of the flies, meaning less food for shrimps. therefore less breeding of shrimps)
