Physics Help?

Question

A fireman at a a horizontal distance of 25.0 m away from a burning builiding directs a stream of water from a fire hose to the building. The hose is 1.20 m above ground; the strean leaves the hose with a speed of 20.0 m/s at an angle of 60.0 above the horizontal. At what height above the ground does the stream of water strike the builiding?

 

Answer 1

Step 1:

The horizontal distance between fireman and building is d = 25 m.

The hose is 1.20 m above ground.

The initial speed of the stream is .

The angle of the hose above the horizontal is .

Find the height of stream of water strike the building.

The components of the initial velocity are

Step 2:

The flow of the water stream is in projectile motion as shown in figure.

Horizontal acceleration is zero in projectile motion.

So we have .

Where is change in distance.

So the time taken to strike the building is 2.5 s.

Step 3:

Now find the vertical height.

The vertical height of stream of water strike the building is 12.675 m.

Solution:

The vertical height of stream of water strike the building is 12.675 m.