physics help?

Question

A kayaker paddles with a power output of 50W to maintain a steady speed of 1.50m/s. (a)Calculate the resistive force exerted by the water on the kayak. (b) If the kayaker doubles her power output, and the resistive force due to the water remains the same, by what factor does the kayaker's speed change.

Answer 1

Not going to do your problem for you, but you can solve it by going back to understand how power is defined in physics.

Power is equal to work done per unit time. Work is force times distance. So power is forces times distance divided by time. Distance divided by time is velocity. So power is force times velocity.

You know power. You know velocity. You can calculate force.