What Is the Rate of Change of Momentum When Water Hits a Building?

[CASHMONEY]

Tried this problem, but not getting it.

Homework Statement

A fire hose sends 2528 gallons of water per minute against a building. The water strikes the building at 28 m/s and does not bounce back. What is the magnitude of the rate of change of momentum of the water?

Homework Equations

The Attempt at a Solution

I used the conversion factor of 1 gallon / 3.7856 L and 1 kg / 1 L to find how many kg of water per minute. Then divided by 60 to find how many kg of water per second. I got 159.5 kg of water per second. Then I multiplied by the velocity to get 4466, but I did not get it correct. Am I on the right track or missing something? PLEASE HELP!

 

[Shooting Star]

You seem to be doing it correctly. Check your arithmetic once more.

 

[Moetasim]

Hi there,

It looks like you're on the right track, but you may have made a mistake in your conversion. Let's go through the steps together:

1. First, we need to convert 2528 gallons per minute to liters per second. We can do this by multiplying 2528 by the conversion factor of 3.7856 liters per gallon. This gives us 9586.048 liters per minute.

2. Next, we need to convert liters per minute to liters per second. We can do this by dividing 9586.048 by 60 (since there are 60 seconds in a minute). This gives us 159.76746 liters per second.

3. Now, we need to convert liters to kilograms. We can do this by multiplying 159.76746 by the conversion factor of 1 kg per liter. This gives us 159.76746 kg per second.

4. Finally, we can calculate the rate of change of momentum by multiplying the mass (159.76746 kg per second) by the velocity (28 m/s). This gives us a rate of change of momentum of 4474.74168 kg*m/s.

I hope this helps! Let me know if you have any other questions.