# Can anyone help me out on the simple pendulum lab?

• exparrot
In summary, the conversation discussed the difficulties of calculating the percentage difference between theoretical and experimental velocity in a simple pendulum lab. The person was struggling to find the velocity from their experimental data and had attempted to use the conservation of energy and arc length, but their results were significantly different from the theoretical value. They mentioned the need for a second time and length to determine speed from the photogate data. They expressed frustration and requested assistance.
exparrot
For the simple pendulum lab, I have to find the percent difference between my theoretical and experimental velocity. I found out my theoretical velocity as I used the conservation of energy to generate an equation for v, but I'm having a hard time calculating my velocity from my experimental data! So what happened was that a bob was swung at different angles (10° to 60°) with the bob going through a photogate. The time recorded was the time the moment the bob entered through the photogate. Using this time and other data present (pendulum length, radius of bob...) I have to find velocity, BUT I have no clue how to do so. I tried to find my time by finding the arc length (the length of the path traveled by the bob) divided by my time, but my answers are so way off from my theoretical. I really don't know what to do and I'm so frustrated... I would really appreciate if anyone could help me out on this one! Thank you!

exparrot said:
... The time recorded was the time the moment the bob entered through the photogate. Using this time and other data present (pendulum length, radius of bob...) I have to find velocity, BUT I have no clue how to do so. ...
One time is not sufficient to to extract velocity information from experimental data. The first time a photogate beam is interrupted, a clock starts running (that's t = 0). You need a second time and a length to determine speed. Exactly what times did you record?

Last edited:

Hello, it sounds like you are having some difficulty with your simple pendulum lab. It can be challenging to calculate the experimental velocity using the data you have collected, but there are a few steps that can help you get closer to the theoretical velocity.

First, make sure you are using the correct formula for calculating velocity in a simple pendulum. It is v=√(gL(1-cosθ)), where g is the acceleration due to gravity, L is the length of the pendulum, and θ is the angle the pendulum is released from.

Next, double check your measurements for accuracy. Make sure you are using the correct length and radius for your bob and that your angle measurements are precise.

You mentioned using the photogate to record the time the bob entered through it. This is a good method, but make sure you are starting the timer as soon as the bob passes through the photogate, not when it reaches the bottom of its swing.

It is also important to make sure your pendulum is swinging freely and without any outside forces acting on it. This can affect the accuracy of your results.

If you are still having trouble, try taking multiple measurements at each angle and averaging them to get a more accurate result. You can also try using a different method, such as using a stopwatch to time the pendulum's swings.

Overall, it is important to be patient and persistent when conducting experiments. Don't get discouraged if your results are not exactly matching the theoretical values. Keep trying and make adjustments as needed. Good luck with your experiment!

## 1. What is a simple pendulum?

A simple pendulum is a weight suspended from a pivot point that can freely swing back and forth. It consists of a mass (the weight) and a string or rod (the pivot point) and is used to study the effects of gravity on an object's motion.

## 2. What is the purpose of a simple pendulum lab?

The purpose of a simple pendulum lab is to investigate the relationship between the length of a pendulum and its period (the time it takes to complete one full swing). This lab can also be used to calculate the acceleration due to gravity in a particular location.

## 3. What are the materials needed for a simple pendulum lab?

The materials needed for a simple pendulum lab include a weight (such as a small ball or block), a string or rod, a stopwatch or timer, a ruler or measuring tape, and a stand or clamp to suspend the pendulum from.

## 4. How do you perform a simple pendulum lab?

To perform a simple pendulum lab, you will need to set up the pendulum by suspending the weight from the pivot point and measuring the length of the string or rod. Then, you will release the pendulum and use a stopwatch or timer to record the time it takes for the pendulum to complete one full swing. This process is repeated for different lengths of the pendulum to collect data for analysis.

## 5. What can we learn from a simple pendulum lab?

A simple pendulum lab can teach us about the relationship between the length of a pendulum and its period, as well as how the acceleration due to gravity affects the motion of objects. It also allows for the application of mathematical concepts, such as calculating the period and acceleration due to gravity using the collected data.

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