Calculating Minimum Velocity for Knocking Down a Burning Building Door

[alessandro]

Homework Statement

a fire hose is turned on the door of a burning building in order to knock the door down. This requires a force a 1000 N. if the hose delivers 40 kg per second, what is the minimum velocity of the stream needed? assuming the water doesn't bounce back?

Homework Equations

The Attempt at a Solution

1000:40=25

 

[aim1732]

Although you did not show your attempt clearly, it would help if you thought a thousand Newton of force as 1000 kg-m/s momentum gained/lost per second. Since water does not bounce back, it loses all momentum on the door and hence exerts a force.The rate of flow of water is given so could you find force it would exert on the door assuming velocity to be v?