The power p kW needed to run a boat varies as the cube of its speed s m/s. If 400 kW will run a boat at 3 m/s, what power is needed to run the same boat at 5 m/s?​

What creates an electric force field that moves electrons through a circuit? a. energy sourceb. loadc. metal wiresd. resistance

Which of these best describe the perceived body image of a person suffering from anorexia nervosa? a.accurate b.healthy c.normal d.overweight

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.