# HW help

1. Nov 24, 2004

### HurricaneH

HW help:(

Any help will be appreciated.

1. Water flows over a section of Niagara Falls at a rate of 1.2x10^6 KG/s and falls 50m. How many 60W bulbs can be lit with this power?

2. A bullet with a mass of 5g and spped of 600m/s penetrates a tree to a depth of 4cm. Determine the frictional force that stops the bullet. Determine how much time elapsed from the moment the bullet entered the tree and the moment it stopped.

:(

2. Nov 24, 2004

### Leo32

1. Calculate how much potential energy that mass of water turns into kinetic energy when it falls down per second. This kinetic energy is the power that you could ideally take out of it. This should get you started. Feel free to post your solution or assumptions here for a reality check.

2. Study this also from an energy standpoint. What is the kinetic energy and potential energy of the bullet before it strikes and after it has come to a stand still ? Friction will take away any energy loss.

Regards,
Leo