Power: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Power. Understanding the underlying formula is key to arriving at the correct answer below:

Mass flow rate is $\frac{dm}{dt} = \lambda v = 100 \times 2 = 200\text{ kg/s}$. Power of the engine equals the kinetic energy given to water per second: $P = \frac{1}{2}\left(\frac{dm}{dt}\right)v^2 = \frac{1}{2}(200)(2)^2 = 400\text{ W}$.