Question

A kayaker paddles with a power output of 490 W to maintain a steady speed of 1.50 m/s. What is the resistive force exerted by the water on the kayak?

Answer 1

`326.6"N"`

Explanation:

Using dimensional analysis:

Watts = `"N"."m.s"^(-1)`

`:.("N".cancel("m.s"^(-1)))/(cancel("m.s"^(-1)))="N"`

`:.F=490/1.5=326.6"N"`

Answer 2

I found `163.3N` but check my method (whether it makes sense or not!).

Explanation:

Have a look:

I considered the fact that the kayaker has to put energy to push the kayak and to overcome water resistance...I think.