Another physics problem that I do not know where to start

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Homework Help Overview

The problem involves a scenario where water is squirting horizontally from a hole in a dyke, and participants are tasked with determining various parameters such as time in the air, distances, and velocities related to the water's motion. The subject area primarily involves kinematics and fluid dynamics.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between the horizontal motion of the water and the vertical fall due to gravity. Questions arise about how to calculate the time of flight, horizontal speed, and the relationship between pressure, area, and depth of water.

Discussion Status

Some participants have offered insights into the equations of motion and the effects of gravity on vertical motion. There is an ongoing exploration of how to relate the horizontal speed to the pressure at the hole and the area of the hole. Multiple interpretations of the problem are being considered, and guidance has been provided regarding the use of kinematic equations.

Contextual Notes

Participants express uncertainty about the equations needed to solve the problem and the connections between different physical concepts, such as pressure and velocity. There is also a mention of the initial conditions of the water stream and its horizontal trajectory.

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Homework Statement


A small dutch boy, Hansel, and his little sister, gretal, were walking home from school along a polder when they saw a stream of water squirting horizontally fom a hole in the dyke. Hansel used a meter stick and found that the hole was a distance Y1= 1.05 m above the polder and that the water landed a distance X1= 1.51 meters from the base of the dyke. Hansel sent gretal running for help and stuck his finger, which had a cross sectional area A1= 1.00 cm^2 into the hole. While hansel waited for help, hansel established a crtesian coordinate system with +x in the direction of the stream and +y up with the origin at the polder.
(A) Time, T, the water was in the air
(B) the distance of the hole, Y2, below the surface of the north sea.
(C) the velocity Vo,x of the water as it exits the hole
(D) The velocity, V, of the water as it hits the polder
(E) The cross sectional area, A, of the stream of water as it hits the polder

Homework Equations


the velocity and time equations need to be used


The Attempt at a Solution



I have been trying the past week to solve this problem and I do not know what equations I am suppose to use and how I am suppose to find them. I am completely lost on this problem and any help would be wonderful.
 
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dban33 said:

Homework Statement


A small dutch boy, Hansel, and his little sister, gretal, were walking home from school along a polder when they saw a stream of water squirting horizontally fom a hole in the dyke. Hansel used a meter stick and found that the hole was a distance Y1= 1.05 m above the polder and that the water landed a distance X1= 1.51 meters from the base of the dyke. Hansel sent gretal running for help and stuck his finger, which had a cross sectional area A1= 1.00 cm^2 into the hole. While hansel waited for help, hansel established a crtesian coordinate system with +x in the direction of the stream and +y up with the origin at the polder.
(A) Time, T, the water was in the air
(B) the distance of the hole, Y2, below the surface of the north sea.
(C) the velocity Vo,x of the water as it exits the hole
(D) The velocity, V, of the water as it hits the polder
(E) The cross sectional area, A, of the stream of water as it hits the polder

Homework Equations


the velocity and time equations need to be used


The Attempt at a Solution



I have been trying the past week to solve this problem and I do not know what equations I am suppose to use and how I am suppose to find them. I am completely lost on this problem and any help would be wonderful.
The water starts moving horizontally. What causes it to fall to the ground (polder)? How far does it fall? How long does that take? You know the horizontal distance traveled in that time, so what is its horizontal speed?

How is the horizontal speed of the water related to pressure at the hole and the area of the hole? How is the pressure related to the depth of the water at the hole?

Answer those questions and you will solve each point.

AM
 
Gravity causes it to fall. It falls 1.05 meters. I do not know the time because that is what I am trying to find. How do I find the horizontal speed? I also don't know how the speed is realted to the pressure and the area of the hole or the depth of the water at the hole.

What are the equations I use to find the time, distance, velocity, and the cross sectional area??
 
x = ut +(1/2)*at^2.

Since the water stream is initially traveling horizontal (ie vertical component = 0)
a = acceleration due to gravity
x = 1.05 m. Solve for t.

Also gravity is a force that only affects vertical motion - it has no effect on horizontal motion. So once you have the time, a simple velocity = distance/time calculation will give you the horizontal velocity, ignoring air resistance.
 

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