Ans: When large amount of water ejects from the hose pipe with high speed in the forward direction (say, action force), then the water exerts a reaction force in the backward direction (reaction force). This reaction force tends to move the hose pipe in the backward direction.
How do you calculate the force of a fire hose?
Hose End Force Chart. Force is the dynamic power which is exported longitudinally through a hose, towards the ends. To arrive at the number of pounds of force exerted, you merely multiply the area of the I.D. times the working pressure being used (Force = Area x Pressure).
Why might it be hard for the firefighter to hold the hose steady when the water gushes out of the hose think about the law of conservation of momentum?
This is because of Newton’s third law of motion. As a result of the backward force, the stability of the fireman decreases. Hence, it is difficult for him to remain stable while holding the hose.
Why it is difficult for a firefighter to hold a hose which ejects large amounts of high speed water?
Newton’s third law of motion states that every action has an equal and opposite reaction. Hosepipes eject a large amount of water at a high velocity. There’s a backward reaction force due to the water rushing out. This tends to decrease the stability of the fireman, thus making it difficult for him to hold it.
Why are firemen thrown backwards when water gushes out of the hose?
Explanation: The answer is “a fireman turns on a hose and is knocked backwards” because the force of the water going out of the hose is equal and opposite to the force pushing backwards on the fireman. Newton’s 1st Law: The law of inertia. Inertia is an objects tendency to resist changes in motion.
Why does a hose pipe tend to move backward when the fireman direct a powerful stream of water towards fire?
When a fireman directs a powerful stream of water on a fire,the hose pipe tends to go backward due to the reaction force of the water rushing through it in the forward direction at a great speed.
What is the flow rate of a fire hose?
A 1 3/4-inch handline can flow up to 325 gpm using one firefighter with a 1 1/4-inch smooth bore tip or a fog nozzle. 20. A 2-inch handline can flow up to 400 gpm using two firefighters with high- pressure hose and a 1 1/2-inch tip at 50 psi NP.
How much water will the fire hose discharge?
Most hose reels are designed to deliver 30 litres of water a minute or 0.33 litres every second, but Australian Standards specify that the 19mm fire hoses have to be able to deliver at least 0.45 litres of water per second, at 220kPa.
What is the friction loss in a fire hose?
Friction loss is nearly independent of pressure. Friction loss varies with type, lining, weave, quality, and age of the hose. Friction loss increases 4 times for each doubling of water flow. Reducing the diameter of a hose by 1/2 will increase the friction loss by a factor of 32 for the same flow.
Why does a fire hose recoil when the water is turned on?
The reason why the hose moves backward is that it is pushed backward by a reaction force when the water is forced out of the hose. The hose and water are not in motion before the water is turned on; therefore, no momentum is created by the hose/water system.
Which law of motion is being explained by this situation the valve of a water hose is opened as water spurts out the hose is thrown backward?
Explanation: According to Newton’s third law, in every interaction, for every action there is a reaction that is of equal magnitude and opposite direction. In this case, as the hose water gushes forward, a reaction force is applied by the water on the hose, meaning that there is a backward force applied on the hose.
When fighting fires a firefighter must use great caution to hold a hose that emits large amounts of water at high speeds Why would such a task be difficult?
When fighting fires, a firefighter must use great caution to hold a hose that emits large amounts of water at high speeds. Why would such a task be difficult? The hose is pushing lots of water (large mass) forward at a high speed. This means the water has a large forward momentum.
Why does fireman hold the hose pipe tightly?
When fireman directs a large amount of water at a high velocity on fire from a hose pipe, they have to hold the hose pipe strongly because of its tendency to go backwards.
Why firefighters have a jet attached to the head of their water pipe?
to increase the velocity of water flowing out of the pipe.
What is Newton’s third law of motion?
Newton’s third law simply states that for every action there is an equal and opposite reaction. So, if object A acts a force upon object B, then object B will exert an opposite yet equal force upon object A.
How does first law of motion lie in second law of motion?
Answer: Newton’s First Law of Motion states that a body will stay at rest or continue its path with constant velocity unless an external force acts upon it. Newton’s Second Law of Motion states that the net force that acts upon a body is equal to the mass of the body multiplied by the acceleration due to the net force.
Why do action and reaction forces not cancel each other?
You might think that because action-reaction forces are equal and opposite that they cancel. However, action and reaction force pairs don’t cancel because they act on different objects. Forces can cancel only if they act on the same object.
What pressure do you test fire hose at?
Attack fire hose should be service tested to a minimum of 300 psi or a service test pressure marked on the hose. Supply fire hose should be service tested to a minimum of 200 psi or a service test pressure marked on the hose.
How do you calculate flow through a hose?
- Formula. Q = (1946.6 * D ^ 1.857 * (P/L) ) ^ .54.
- Inner Diameter.
- Length.
- Dyanmic Pressure at Bib.
How fast does water come out of a fire truck hose?
These lines are located directly below the pump panel. They lay out in the open and are light, so they are easy to get off the fire engine for attacking a fire. Crosslays are 200 feet (61 m) long, have a diameter of 1.5 inches and can gush water at 95 gallons (360 L) per minute.
Does hose diameter affect water pressure?
In general, a smaller hose will increase the water pressure. The smaller the pipe, the more resistance the water will see. A 3/4″ hose will see a decrease of around 2 PSI per 100 ft. A 5/8″ hose will see a 4 PSI decrease.
How much water can flow through a hose?
A typical garden hose flow rate is usually between 9 and 17 gallons per minute. The average garden hose GPM would be around 12 to 13, but this can vary depending on the type of hose.
How do you calculate pressure loss on a hose?
Pressure loss is directly proportional to hose length. Since the flow charts are based on 100′ lengths, loss for 100′ must be converted to 150′ of hose. Pressure loss for 100′ of hose is 20 psi, therefore, the loss in 150′ of hose is: 150’/100′ x 20 psi = 30 psi.
How does friction loss affect a water supply?
If you have too much friction loss, it can wear down your pump or reciprocating compressor. Friction forces your pumps to work harder to push fluids through clogged pipes. That extra effort means your valuable energy-producing technology can become overworked and break down faster.
What is caused by friction loss?
The head, pressure, or energy (they are the same) lost by water flowing in a pipe or channel as a result of turbulence caused by the velocity of the flowing water and the roughness of the pipe, channel walls, or restrictions caused by fittings.