How Fast Does a Trebuchet Counterweight Travel?

In summary, Dale is building a mechanical launching device and needs to know how fast his counterweight will be traveling. He provides the travel time to reach each point (1, 60 & 120 in.), as well as the speed at which the counterweight will be traveling. Finally, he requests a formula to be used to calculate the speed and distance, but provides no information to actually do the calculations.
  • #1
dalebennett
4
0
Hey Smart Guys,

At age 61, I am building a mechanical launching device (Trebuchet) and I need to know how fast my counterweight will be traveling.

How fast will it be traveling after 1 inch
How fast will it be traveling after 60 inch
How fast will it be traveling after 120 inch

Also, please provide the travel time to reach each point (1, 60 & 120 in.)

The counterweight surface is flat, weighs 2000 lbs with a square surface area of 1296 Sq Inches. (3'x3')

I don't do formulas very well, so plain English would be much appreciated!

Thanks in Advance,

Dale
 
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  • #2
dalebennett said:
Hey Smart Guys,

At age 61, I am building a mechanical launching device (Trebuchet) and I need to know how fast my counterweight will be traveling.

How fast will it be traveling after 1 inch
How fast will it be traveling after 60 inch
How fast will it be traveling after 120 inch

Also, please provide the travel time to reach each point (1, 60 & 120 in.)

The counterweight surface is flat, weighs 2000 lbs with a square surface area of 1296 Sq Inches. (3'x3')

I don't do formulas very well, so plain English would be much appreciated!

Thanks in Advance,

Dale

Fg=Ek

Force of gravity will convert to Kenetic energy

mgh=1/2mv^2

solve for v
(Devide both sides by m, multiply by 2 and sq rt both sides)

v=sqrt/ 2gh

EDIT: g=gravity at 9.8m/s and h is height in meters and v is also in meters/second

When you find speed you already have distance

v=d/t

t=vd

Multiply the speed in m/s and distance in meters to get the time
 
  • #3
There will be some energy lost to friction so the above analysis gives a high estimate. If you need better you will need to figure out a way to measure the velocity.
 
  • #4
I'm sorry, but I don't understand these equations. Would you be kind enough to do the actual calculation. I flunked out of algebra.
 
  • #5
The answer depends on what kind of trebuchet you want to build. In addition, you need to specify things like the length, weight and shape of the beam and where the axle is in relation to both the counterweight and payload.
 
  • #6
Actually, I just want to use this information as a reference point. For now, all I need are the raw answers. Please, just disregard the Trebuchet design for now. If you are interested in this project, I would be extremely interested in providing you more detail a little later.

This is a new concept for a Trebuchet and there are many physics questions that will need to be answered. For now, just the basic math, please.

I'm planning a 1 mile launch that has never been done before.
 
  • #8
I copy/pasted that equation exactly as show into Excel and it did NOTHING.

Is '1 inch' suppose to be embedded into the equation?

What value do I change. I'm am truly sorry for my ignorance.

Can you give it EXACTLY as it should be put into an excel cell - for 1 in and 2 inches - then I will know how to modify the equation for any distance?

the following was the last thing I tried.

=sum(sqrt(2*(9.8(m/(s^2)))*1))

Obviously, I don't know what I'm doinh

Thanks for your patience.

Dale
 
  • #9
http://www.uni-siegen.de/fb11/nm/aktuelles/downloads/trebuchet_adams.pdf [Broken]

This might be useful for you, in particular the model described in figure 5(c).
 
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  • #10
In the absence of any design specifications the best you can do is set limits for speed and time based on a free falling counterweight.

For what it's worth, here's what you get for the numbers:

1 inch: Max speed = 2.3 feet per second, Min time = 0.072 seconds
60 inch: Max speed = 18 feet per second, Min time = 0.56 seconds
120 inch: Max speed = 25 feet per second, Min time = 0.79 seconds
 
  • #11
dalebennett said:
I copy/pasted that equation exactly as show into Excel and it did NOTHING.

That wasn't intended to be used in excel. Google has a built in calculator that understands units and constants. If you click the link you should see 1 inch gives an answer of 1.578 mph. If you want to change the distance you do so in the Google search box. You should notice that if you, for example, change 1 inch to 3 feet the answer pops up in a box directly below the search box. You don't even have to click search.

If you want to use excel the formulas should be:
Code:
=SQRT(2 * 32.174 * 1) <- one [B]foot[/B], answer is 8.02 [B]feet[/B] per second
=SQRT(2 * 32.174 * 2) <- two [B]feet[/B], answer is 11.34 [B]feet[/B] per second
=SQRT(2 * 386.09 * 1) <- one [B]inch[/B], answer is 27.79 [B]inches[/B] per second
=SQRT(2 * 386.09 * 2) <- two [B]inches[/B], answer is 39.3 [B]inches[/B] per second
Pay careful attention to the difference between inches and feet in the above forumulas. Like I said, Google understands units and does the conversions for you. Excel does not, and you have to manually do the conversions.
 
  • #12
There's a trebuchet simulator that is probably more useful for you:

http://www.trebuchet.com/sim/ [Broken]
 
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1. What factors affect the speed of a falling object?

The speed of a falling object is affected by the gravitational pull of the Earth, the mass of the object, and the air resistance it experiences during its fall. Objects with greater mass and less surface area experience less air resistance and will fall faster than lighter objects with more surface area.

2. How does air resistance affect the speed of a falling object?

Air resistance, also known as drag, is a force that opposes the motion of a falling object. As the object falls, it pushes against the air molecules in its path, causing them to exert a force in the opposite direction. This force increases as the speed of the object increases, eventually balancing out the force of gravity and causing the object to reach a constant speed known as the terminal velocity.

3. How is the speed of a falling object calculated?

The speed of a falling object can be calculated using the formula v = gt, where v is the final velocity, g is the acceleration due to gravity (9.8 m/s² on Earth), and t is the time it takes for the object to fall. This formula assumes that air resistance is negligible.

4. Does the mass of a falling object affect its speed?

Yes, the mass of a falling object does affect its speed. Objects with greater mass experience a greater force of gravity, causing them to accelerate faster than lighter objects. However, as mentioned before, the amount of air resistance also plays a role in determining the speed of a falling object.

5. How does the height from which an object is dropped affect its speed?

The height from which an object is dropped does not directly affect its speed. However, the greater the height, the longer the object has to accelerate due to gravity, resulting in a higher final velocity. This is because the object has more time to gain speed before reaching the ground.

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