Why is it important to have a control when making an experiment ? Also no web search or I will report so put it in own words answer ASAP please

Agenerator converts mechanical energy to electrical energy. when a coil placed between two magnets rotates, the magnetic lines of force are disturbed. this induces a current in the coil. the image below shows a generator. what could be done to make the lamp brighter? a. decrease the size of the magnets b. turn the coil slower c. change the polarity of the magnets d. turn the coil faster

Bone-strengthening physical activity done increases bone-mineral content and bone density in youth.

Aquarterback pedals 3.3meters southward and then run 5.7meters northward. whats the distance ? and whats the displacement?