Lab 9: circuits

Lab: 9 circuits

To experiment with and learn more about circuits we hooked up an ammeter to a power source and began experimenting with how resistors, light bulbs, and changing the amount of resistors affected the voltage going through the wires. After experimenting with a light bulb we measured the voltage of the wire after it had gone through the light bulb and found that voltage seemed to increase linearly with the amps, or as we increased the power the brighter the light bulb seemed to get, logically this made sense. Thus we made the argument that all of the system would follow the same principle.

This however proved untrue when we added in a second resistor. After adding a second resistor we found that the voltage began to experience an exponential growth. This seemed to be based on how and when the resistors began absorbing the charge and how much began to go through at a time. As the amps increased the voltage being stopped and regulated by the resistors seemed to be mixed up by the second resistor, changing the voltage increase from a linear one to an exponential one.

Thus our original prediction was proven false, the information managed to both contradict and support our original experiment. The voltage in the current did increase based on the amps provided, but were limited in differing amounts based on the amount of resistors in the wiring.

Problems and issues

an unfortunate problem we had was that the voltage would change roughly based on how much pressure and where we placed the attaching clamps on the resistor or how tightly we held the wires to the light bulb. this could have disrupted some of out data an information, but not likely enough to disrupt the entire results.

Lab 8: Electrostatics

Lab 8: Electrostatics

There are many ways to test Electrostatics, but some of the best ways to test and explain them is through Pith balls and electroscopes. Pith balls are two lightweight “pith” balls suspended from the strings are attracted to objects with a static electric charge. The pith balls can also be charged by touching them to an object with a static electric charge. 

                                                           

Electroscopes are device used to detect the presence of charge and its relative amount. They are usually constructed with a metal plate or sphere at the top of a metal post with a metal rod hanging from the bottom of the post.

                                                             

These two are charged with differing charges making them very reactive to differing electrical energy and charges that come near to them. This can be caused by the movement of the electrons within the instrument which cause the lighter materials in the instrument to move towards or away a grounded rod that is brought close to it. These instruments will react differently but can be easily understood. We experimented with this in class by grounding several rods with alternating charges and touching and moving the rod around the instruments to see how they react. This can be used to discover the charge of the object by checking how the instruments react, if they are opposite to the object then balls will be attracted to each other and move towards each other, while if they are similar to each other they will be pushed away from each other. In turn an electroscope will move when an electrically charged and grounded object moves near it and will actually stay in an elevated position due to the electrons being transferred to the electroscope through the contact. 

These two instruments are effective at serving as an effective way to test objects in their own way, pith balls can show whether an object has a positive or negative charge, while a electroscope can show the strength of the charge by how it stays up when charged. Thus these instruments are very useful when testing for and find unknown charges.

Lab 6: Energy part one

Lab 6: Energy part 1

To experiment with work and how it affects the energy, velocity, and movement of an object. To do this we set up a friction less track with a slider and weights and began alternating the height and placement of the slider on the track. We would then change the amount of force we exerted on the cart and monitor how fast it traveled a see how that affected the work done. We recorded this information into logger pro, here is an example of the difference between a forceful shove and actually fighting the weights to let the cart fall slower.

The data was partially conclusive with our initial prediction, that more force would move the track faster, but this did not vastly change the integral, averaging on a few 10ths of a joule where a joule is equal to Mass*Newton’s like we had thought it would. 

To expand on this we set the track up as a ramp to test out and see if height or displacement would have any effect on the integral. We varied our height by about 20cm by first testing the slider from 70 cm to 190, and then from 90cm to 190cm. our results are below, and served to concur with our prediction.

We then elevated to track and increased the incline of the ramp and used the same two distance markers.  The heights were different at the same points along the ramp at 90 cm (8.8 cm vs. 10.2 cm).  We compared the integrals and found that height does matter= .3243J vs .2074J for the first trial at a lower incline, as shown here.

These experiments show us that height matters when it comes to work being done.  Potential energy is higher when the incline is higher.  Varying force seems to not affect the work when the distance (displacement) is the same.  This all ties into work done in order to change energy in a system.

Possible issues.

One of the greatest issues we had with the experiment was ensuring that the track stopped smoothly. With such a short track we were forced to abandon several graphs due to this problem as the tracks would flip backwards and disrupt the information, making the graph useless and corrupting the integral measurement. 

Lab 5: Circular motion

Lab 5: Circular motion 

For lab 5 we were asked to find the mass of an object spinning in a circular motion. In order to properly test this we used the DMV Player program Motion in a circle.

To first calculate the mass we needed to find the object velocity.  We set the graph to 30 FPS and monitored the simulation to see how long the graph would take to send the object in a complete circle. We calculated it to take 724 frames to complete its rotation, thus meaning it took 24 seconds to complete its circle. 

The simulation then provided us with the force of the movement up in the top center. We were then able to calculate the velocity of the object by using the rotation motion equation, v=2piR/time, or plugging the numbers into it v=2pi60/3.016, giving us a velocity of 1.25 centimeters. 

We are then able to calculate the acceleration using velocity/radius to get an acceleration of 2.6 MPS. We were then able to plug this into the traditional force formula, F=MA, or in this case 1.15=m*2.6, which we can divide our acceleration into the force for 1.15/2.6=M, or .44Kg of mass for the object.

Errors

Possible errors that could change our results were rounding errors, improper conversions between centimeters and meters.

Lab 4

For lab 4 we were asked to find the initial acceleration of an elevator when it starts and stops. To do this we were given a force probe attached a 550 gram weight and stand that would measure the change in force as the elevator accelerated. 

Before we could do this we had to first calculate the amount of force that gravity was putting on the probe itself in order to subtract it from our findings in the elevator. After zeroing the probe we found that gravity placed roughly 5.1 newton’s of force on the probe, with this information in hand we quickly sketched a set of a motion diagram, force diagram, and force addition diagram. We calculated that the elevator would have its forces cancelled out by both the tension in the cable and the force of gravity until the moment of acceleration, at which point the motor in top of the elevator shaft would either increase tension to make the elevator go up or decrease it to make it stop and equalize. We would then be able to calculate the elevators acceleration by dividing the change in force by the velocity, giving us the acceleration.

Armed with this information we proceeded to the elevator and took a single reading from the start of the elevators trip to the bottom to its stop at the bottom floor that provided the following chart from logger pro.

From this information we were able to discover the force at the time of acceleration at the elevators beginning and ending. Logger pro calculated the force at approximately 5.1 at the beginning as the elevator traveled downwards and increased to 5.8 at its stop in order to counteract its velocity downwards and 5.3 for its constant movement. We then subtracted the constant force of gravity, 5.1 from each reading to find the change in force, calculating to -.3 net force for the initial downwards acceleration and a .4 increase for the upwards acceleration to cease moving and a constant .2 difference. 

We then plugged this information into the formula Weight*Acceleration=Force, giving us 550*A=5.1, which after dividing the force by the weight to isolate acceleration gave us 0.009 Meters per second for start, and then did the same for its acceleration to stop, calculating to 0.010, keeping the force relatively the same for the elevator. To calculate the speed of the elevator we divided this number by the weight of the weight attached to the recorder in kilograms, calculating that the average speed of the elevator was .36 Meters per second. A fairly comfortable pace for an elevator that takes roughly 9 seconds to go between floors.

Possible problems.

Gaining the information for an elevator is not always exact as it can be difficult to time the movement of the elevator with when the graph starts and ends, we were lucky, but we may have missed some critical data. Additionally we always needed to take the averages of the information and that can sometimes be skewed by large temporary readings, like the short hikes that the graph shows for the initial movements of the elevator.

Lab 3: Forces

For lab 3 we experimented with forces and motion and how they could affect and change the acceleration and velocity of an object. The final result of this was an experiment that monitored the change in velocity as more weights were added to double the amount of force being used to pull the slide, as can be seen below. In order to create a controlled and uncontrolled system to compare the results to we used compressed air to create a friction-less environment and then used the rail base to compare how friction can change an objects velocity.

To support these findings we also experimented with changing and varying the amount of newtons to pull a car and see how its acceleration changed, seeing that the value increase with the amount of force applied.

 

These experiments tied into the very first experiment we did where we experimented with changing the location and amounts of force exerted on a bowling ball to see how we could influence it. constant force would create constant acceleration while when provided with a much more loose or reduced friction environment, or constantly maintained force to produce a constant velocity. The secondary experiments supported this with the first one providing an example of changing force and the second and example of constant force, supporting the statement that all motion is based on the force behind it.

Lab 2, APPLICATION EXPERIMENT: WHAT KIND OF MOTION?

For lab 2 we were assigned to find whether a provided coffee filter would fall at a constant speed,
constant acceleration, or changing acceleration. In order to do this we decided to place a motion detector on the floor and align said coffee filter with the reader above it and drop it onto the motion detector. After several tries that caused the filter to drift off of the scanner and disturb our results we elected to place several filters together in order to give the object more mass and allow it to fall straighter without being disturbed by passing persons or air currents. The result of this can be found below.

Our results were then recorded and we compared the slope of the graph to calculate its constant rate of motion to determine its rate of motion and if that rate changed or was constant, representing whether its fell constant speed, constant acceleration, or changing acceleration.

We began with an over view of the movement.

As can be seen on the graph the coffee filter slowly begins to accelerate in its constant motion due to its increase in its acceleration downwards. this rules out the question of whether the filter falls at constant speed.

In these next two we can see that the velocity and position are constantly changing, by definition ruling out the possibility of constant acceleration as the rate is not constant, rather changing. Thus we can surmise that the coffee filter falls with a changing acceleration until it hits the floor, at which point it achieves a quite constant and unchanging acceleration of zero as it is resting in place.

Problems;

While we did the best we could we acknowledge that there are some problems with this form of measurement. Firstly the most common problem was that the filter was too light and had a tendency to drift off the scanner, invalidating our readings, this can be caused by a simple drift to the right or even a person walking by and disturbing the air. Additionally we were dropping the filter from a height of roughly one meter, a height that serves well as a basis for a smaller measurement but does not allow for terminal velocity to take effect, possibly changing the experiment.