Mass of weight to keep gate closed

In summary: Expert SummarizerIn summary, the conversation is about a problem involving finding the mass of a weight W in a first year fluid dynamics course. The problem involves a hinged gate and the use of the principle of moments to solve for the unknown force acting on the weight W. Steps to solve the problem are outlined, including drawing a free body diagram, writing equations of equilibrium, and using Newton's second law. The expert also reminds the asker to include units and double check their work.
  • #1
jc911
8
0
Hi All,

Cannot seem to figure out the question below. I`ve attached an image of the question.

I basically need to find the mass of the weight W.

The hinged gate will open when the water height is 12ft.

The gate is a 5ft wide L shaped gate, hinged at point A.

I`ve gone down the line of CW = CCW moments but cannot seem to answer this.

Any help greatly appreciated. I really want to understand the entire process behind the calculation so I can work through these problems myself going forward :)

This is first year fluid dynamics.

Thanks,
James
 

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  • #2
Hi James,

Thank you for sharing your question and providing an image of the problem. It seems like you are on the right track by using the principle of moments to solve for the mass of the weight W. Here are the steps that you can follow to solve this problem:

1. Draw a free body diagram of the gate and the weight W. This will help you visualize the forces acting on the system.

2. Write down the equations of equilibrium for the horizontal and vertical forces. This will help you determine the unknown forces acting on the system.

3. Use the principle of moments to solve for the unknown force acting on the weight W. This can be done by taking moments about point A, the hinge point of the gate.

4. Once you have determined the unknown force, you can use Newton's second law (F=ma) to solve for the mass of the weight W.

Remember to always include units in your calculations and to double check your work. I hope this helps and good luck with your fluid dynamics studies!


 

FAQ: Mass of weight to keep gate closed

1. What is the difference between mass and weight?

Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity acting on an object. Mass is usually measured in kilograms (kg) and weight is measured in newtons (N).

2. How does the mass of an object affect its weight?

The greater the mass of an object, the greater its weight will be. This is because the weight of an object is directly proportional to its mass, according to the formula W = mg, where W is weight, m is mass, and g is the acceleration due to gravity.

3. How does the mass of weight keep a gate closed?

The mass of weight keeps a gate closed by exerting a downward force on the gate, which creates a torque that keeps the gate in place. The weight must be heavy enough to counteract any external forces acting on the gate, such as wind or pressure from people or animals trying to open it.

4. How do you determine the appropriate mass of weight for a gate?

The appropriate mass of weight for a gate depends on several factors, including the size and weight of the gate itself, the strength of the hinges and latches, and the potential external forces acting on the gate. It is important to carefully consider these factors and use a weight that is heavy enough to keep the gate closed, but not too heavy that it causes damage or makes the gate difficult to open.

5. Can other methods besides weight be used to keep a gate closed?

Yes, there are other methods besides weight that can be used to keep a gate closed, such as locks, latches, bolts, and springs. These methods may be more suitable for certain types of gates or situations, and it is important to consider all options when choosing how to keep a gate closed.

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