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Problem 4.14 of Serway & Jewett: A firefighter, a distance d from a burning building,
directs a stream of water from a fire hose at angle width=9above the horizontal. If the initial
speed of the stream is width=9, at what height h does the water strike the building?

sachin singh , 14 Years ago
Grade 12
anser 1 Answers
suryakanth AskiitiansExpert-IITB

Last Activity: 14 Years ago

Dear sachin,

This is the projectile motion. The equation which describe the motion along horizontal axis x is the following

where is the x-component of initial velocity.

 

Along axis y we have motion with constant acceleration:

 

In these equations at the initial moment of time the water has zero coordinate.

 

What do we know about the final point: we know only the x-coordinate of the final point – it is x=d. We can substitute this coordinate in the first equation (which describe the motion along axis x):

From this equation we can find the traveled time:

Then we substitute this time into the equation which describe the y-coordinate of the water:

 

This expression gives as the height where the water strikes the building.

 

Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.

All the best.

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Suryakanth –IITB

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