Physics lab 3 - Lab 3 - Little g PDF

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Lab 3 - Little g...

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Samuel Obadina Physics 207 GH2 Lab 3 - Little g Introduction In the lab students used multiple methods of measuring g, (a variable that represents gravity, 9.8m/s^2). Some of these methods were accurate and others were not. Students tried 6 different methods of finding g, relying on units such as meters for the position, seconds for time, and m/s^2 for acceleration. In the real world, we could use this experiment to measure gravity at different altitudes. Also we can use similar experiments to approximate the gravity of celestial bodies in space. Procedure 1- A rough measurement One person holds a wooden block 1 meter from the floor and another person holds the timer. When the person drops the wooden block, the person with the timer will start it. When the wooden block hit the floor, the person with the timer will stop the timer. We then used the equation y= (.5)gt^2 to calculate our prediction of gravity. We used 1 meter for y and our time measured for t, and a negative because the wooden block is falling. After plugging all the variables into the equation, we calculated g for our estimation of gravity. We repeated it 2 more times and found our average out of all 3 times. 2- Slo-mo free fall

This method is similar to the first however we used a video that was recorded in 60 frames per second, then used the frame by frame button to choose a position on the that has measurements of a centimeter in the side for distance traveled. We then used the time from the video to calculate our g. We used the equation y= (.5)gt^2. We plugged in y as the distance traveled in centimeters (which was converted to meters since acceleration is meter per second^2) and we plugged in t for the seconds of the video. We used those two values to calculate the remaining missing variable which was g. 3- leveling a ramp For this experiment, we used the track and car. We adjusted the ramp and used the equation angle =sin^-1(h/l), h representing the height of the opposite side and l representing the length of the adjacent side. The length of the ramp represented our hypotenuse in this case. We set the track so that it is leveled and used the thumbscrews on each end to secure its position. We then confirmed that the track is not moving around by placing the car on the highest point and seeing if it moves. We then kept adjusting the angle until we found the cart sliding down on its own. We then used this data to convert the sides into the angle of the ramp to the floor. 4-The Rolling Cart We used the ramp and the cart and a motion sensor which is connected to a computer to determine the location of a cart at a certain time. We added a block on one side of the track that change the angle of the track and measured its position and time of the car as it moved. Then became recorded on the computer from the motion sensor. We repeated this 2 more times, each time adding a block and increasing the angle. We used the recorded info to find the velocity and acceleration.

5- The Rolling Cart with different masses This experiment is very similar to The Rolling Cart experiment, however we added a weight on the car and then compared the values from The Rolling Cart experiment with this one. For both 5 and 4 we graphed the position and velocity of the car.

Data/ Calculations/ Questions 1- A rough measurement Using the equation For this method, we calculated our average value of gravity to be 10.7 meters per second squared Report Question 1 - Why is this method not very good? What are the limitations? This method is not the best way because humans have a delayed reaction from when the light reaches our retina, to the stimuli reaching our brain, and stimuli reach our hands that press the timer. Also two separate people are either dropping the item and pressing the timer. 2- Slo-mo free fall For this method, we found that our gravity estimation is 9.8m/s^2. We used the equation y=-.5 gt^2 1m = -½ g (0.5) (.45s)^2 g= 9.8m/s^2 3- leveling a ramp For the Leveling a ramp experiment, the value we obtained for what angle is needed for the car to move is .34 degrees which is created by using the inverse sine formula.

Report Question 2 Let's consider how 'level' this track really is. Using uncertainty analysis, what is the uncertainty in the angle measurement of the track? Based on this uncertainty, our tracks are probably not exactly at . In an ideal physics set up, even a very small angle should create an acceleration. So, why can you get the car to stand still? One reason for why the car is standing still even if there is a small angle that should cause the car to accelerate is because there is friction in play. Because the track is not completely frictionless, there will always be a force that will prevent the car from moving unless the magnitude of acceleration is greater than that of fiction. Report Question 3- Based on this angle, estimate the static (or rolling) friction coefficient that is acting on the car when it's on the ramp. The mass of the cart is ~ 500grams. We can calculate the specific value of friction by the equations f = μs N . Because the cart is not moving even though it should be accelerating, there should be some type of static friction. We can calculate this by knowing that the force is going downwards is 4.9N since there is only .5 kilogram. Our angle was 5.0 degrees so we can plug those values in and get out the answer. F/N=u u= ((4.9N)(sin(5))/((4.9)(cos(5)) u=0.087 0.087 should be the estimation of static friction coefficient. 4-The Rolling Cart at different angles The three angles calculated for the rolling car at different angles experiment were 10.88 degrees , 21.76 degrees, and 32.56 degrees. Each of these values represented one trial.

For each angle, and a position and velocity is created. (Figure 1 - Pos 1/Vel 1)( Figure 2 - Pos 2/Vel 2)( Figure 3 - Pos 3/Vel 3) Report Question 4 Figure 1

Figure 2

Fugure 3

5- The Rolling Cart with different masses For the final experiment of the cart with different mass. We found that the values and data given to us were the same per trial. This most likely means that mass does not affect velocity, or it can mean there is a big error in this particular experiment.

Conclusion In conclusion, we were able to use a few different methods to measure gravity, although the first methods provided a human error, we still somewhat accurate with our results....