Which of the following statements is the best argument for daily exercise a. there are many enjoyable forms of exercise, such as jogging soccer, and yoga b: stretching before exercise and 30-45 minutes of activity provides the best results c. for most people, a range of 100 to 120 beats per minute is optimal during exercise d. studies show that people who do not exercise are 50% more likely to suffer from heart disease

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?