PHYS2108 Physics Lab Final

Vectors have: Select one or more: - Direction - Magnitude

- Direction - Magnitude

A 12100 kg railroad car is coasting on a level, frictionless track at a speed of 19.0 m/s when a 4790 kg load is dropped onto it. If the load is initially at rest, find the new speed of the car and the % change of the kinetic energy

- Final speed = 13.6 m/s - Change in KE = -28.4%

Calculate the means and standard deviations of the length, width, thickness, and mass for the plastic object - L: 0.05963 m, 0.05975 m, 0.05973 m, 0.05975 m, 0.05939 m - W: 0.05324 m, 0.05322 m, 0.05346 m, 0.05340 m, 0.05350 m - Thickness: 0.01857 m, 0.01848 m, 0.01893 m, 0.01888 m, 0.01868 m - Mass: 0.07007 kg, 0.07004 kg, 0.07006 kg, 0.07005 kg, 0.07009 kg

- L: mean = 0.05965 m; dev = 1.54x10^-4 - W: mean = 0.053344 m; dev = 1.07x10^-4 - Thickness: mean = 0.018726 m; dev = 1.7x10^-4 - Mass: mean = 0.070052 kg; dev = 1.3x10^-5

What instruments will you use in lab 3? Select one or more: - Slotted Masses - Meterstick - Pulleys - Force Probes - Mass Hanger Pans - Triple Beam Balance - Force Table

- Slotted Masses - Pulleys - Mass Hanger Pans - Force Table

What instruments will you be using in lab 5? Select one or more: - Digital Caliper - Triple Beam Balance - Photogates - Force Sensor - Inclinometer - Meterstick

- Triple Beam Balance - Force Sensor - Inclinometer - Meterstick

In lab 6's lab you will use: Select one or more: - Triple Beam Balance - Stopwatch - Photogates - Inclinometer - Velocity Sensor

- Triple Beam Balance - Photogates - Inclinometer

What instruments will you be using in lab 4? Select one or more: - Triple-beam balance - Accelerometer - Inclinometer - Meterstick - Force sensor

- Triple-beam balance - Inclinometer - Force sensor

Which of the following are valid reasons to take multiple measurements? Select one or more: - You generally end up with a smaller uncertainty in your result - You generally gain precision - You generally gain accuracy - You generally end up with a result closer to the true value

- You generally end up with a smaller uncertainty in your result - You generally gain precision

Which of the following instruments will you be using to make measurements in lab 2? Select one or more: - electronic balance - micrometer - triple beam balance - digital caliper - meter stick

- triple beam balance - digital caliper - meter stick

Calculate the % change from before to after a collision if P(before) = 0.183 and P(after) = 0.170

-7.10

You measure a sheet of paper. The width is 8.47 inches and the length is 11.26 inches. What is the area of the paper in MKS units (m^2)?

0.0615

Calculate the kinetic energy (in J) of a cart with mass 0.5004 kg traveling at a velocity of 0.50 m/s

0.063

The speed of light is 299,792,458 m/s. However, most physicists round this number to 3x10^8 m/s. What is the percent difference in these values using the correct number of significant digits? Assume the exact speed of light is the reference value

0.07%

Calculate the momentum (in kg-m/s) of a cart with a mass of 0.4972 kg traveling at a velocity of 0.44 m/s

0.2188

Calculate the weight of the white cylinder Mass = 0.038 kg

0.3724 N

Calculate the weight of the plastic object from its mean mass. Assume the gravitational constant g is known exactly to infinites significant digits Mass = 0.070052 kg

0.6865 N

Calculate the stored potential energy of the sled at the top of the ramp for the incline m = 1.6787 kg h0 = 0.04 m hf = 0.095 m

0.905 J

External storage manufacturers constantly misrepresent the capacity of their media to consumers. The prefixes k, M, G, and T technically go up by perfect 1000's, but in computer-speak (because it's base-2, not base-10), these prefixes are interpreted as 1024. Translation: If a "kB" means 1000 bytes, a computer will read it as 1000 b/1024 = 0.977 kB. If a "MB" = 1,000 "kB" = 1,000,000 bytes, a computer will see 1,000,000 b = 977 kB = 0.954 MB. Using the above process in converting the bytes to kB, then MB, GB and TB - calculate the usable space on my new 1 "TB" hard drive containing 1,000,000,000,000 bytes in true machine Terabytes. Also compute the percent error between hat I paid for (theoretical size 1 TB) and what I received (your result in TB)

0.909 TB is the amount of TB given which I found by using the factor of the computer actually having 1024 b of data which I divided to become each type of B until I got to b. The percent error is 9.05% which I got by using the equation of percent error and the value that is told by the company which is 1 MB

A billiard ball with mass 4.9 kg is short due west at 2.5 m/s. The ball collides elastically with a second billiard ball, also of mass 4.9 kg. The second billiard ball travels due west, the same direction as the first billiard ball was traveling. Assuming a frictionless table, what is the magnitude of the final velocity of the second billiard ball in m/s due west?

2.5

Think globally. Convert 60 mph (miles/hour) to m/s without the internet. Use only the method introduced in the lab manual and the (hopefully) common knowledge that there are 5,280 ft/mile, 12 in/ft, and 2.54 cm/in. Consider the prefix changes and any conversions for time

27 m/s

Calculate the weight density of the white cylinder Weight = 0.3724 N Volume = 1.36x10^-5 m^3

27382 N/m^3

Humans live an average of 82.5 years in Canada. Express this time in units of days if the conversion factor is exactly 365.2 days. Round your answer to the correct number of significant digits as given by the original time in years (because the conversion factor is known "exactly," meaning to infinite precision

30100 days

Find the percentage of the total work lost to friction if 20.8 J of work is put into pushing a block up a ramp resulting in 14.1 J of stored potential energy at the top. Report the percentage lost as a positive number

32.21

Calculate the volume of the tabletop from the below measurements. Leave your result in cm^3. Record your result in two ways: with and without applying digits. - Length: 150.0 cm - Width: 50.0 cm - Height: 5.0 cm

37,500 cm^3; 38,000 cm^3

Calculate the %-loss in the total work converted to potential energy for the incline W = 1.4784 PE = 0.905

38.8%

In lab we had the work due to friction removing potential energy from a system. Friction can also bleed off kinetic energy. Police use this fact in traffic investigations. Imagine an aspiring young lab coordinator at age 17 getting a rusty '66 pickup ready for a Styx concert when another teenager comes speeding around a corner who dings his sweet ride halfway down the block. The offending vehicle locked its brakes and left an 88 ft long skid mark (as measured by police) on the dry asphalt. As the responding officer on the scene, use the following information from your physics folder (cops actually have these) to determine whether or not to add a ticket for speeding in a 30 mph zone in addition to reckless driving. Cite evidence Coefficient of friction between commercial tires and various road surfaces and conditions: - Dry concrete: 0.68 - Wet concrete: 0.58 - Dry asphalt: 0.67 - Wet asphalt: 0.53

42 mph - would get a ticket

Calculate the volume of the plastic object using V = LWT L = 0.05965 m W = 0.053344 m T = 0.018726 m

5.96x10^-5 m^3

One example of tolerance "that matters in the real world" can be found in radiation oncology clinics. Physicians will prescribe some dose of radiation to a patient's tumor that must be delivered within a certain tolerance (or range of doses) in order to control the tumor. If a physician prescribes 58.0 Gy +/-2.00%, what is the maximum dose the patient can receive (in Gy)? A Gy is measure of the amount of energy deposited per unit mass

59.2

The known area of a table is 1.50 m^2. You measure the length of the table to be 1.30 m and the width to be 1.23 m. What is the percent error between the known area of the table and the measured area of the table you calculate using A = L*W

6.6

Your friend weighs 157.4 lbs. What is your friend's mass in MKS units (kg)? Assume g = 9.8 m/s^2 and 1 lb = 4.448 N and that both of these conversion factors are known *exactly* (for significant digits purposes)

71.44

Calculate the work done on a cart (in Joules) by pulling it a distance of 81.8 cm with a force of 10.60 N parallel to the direction of travel

8.67

Find the percent error between the experimentally obtained mass in the slope of your Force vs. Acceleration curve and the theoretical total mass measured from the balance - Experimental: 0.1114 kg - Theoretical: 1.958 kg

94.3%

Comment on the "efficiency" of storing potential energy as the angle of incline steepens. Explain this behavior. Consider the magnitude of the frictional force as the angle of incline steepens

As the incline steepens, the final height continues to increase. The relationship between height and potential energy in the potential energy equation shows that as the height increases, the potential energy increases as well. This means more and more potential energy will be stored as the height is increased

Compare the statistical uncertainty (standard deviation) of a collection of measurements to the precision of the individual measurements. Generally, what do we lose when we take multiple measurements? Why would you want to take multiple measurements of a quantity any time you can?

As we take multiple measurements we could lose the precision of the results. As we continue to measure we will keep getting different results that could be very different from each other causing us to lose precision. In this way we could possibly lose accuracy as well because there could be a possible error in the measurements if they are not repeated exactly

In an elastic collision, which are conserved? - Momentum - Kinetic Energy - Neither - Both

Both

Add the following two vectors if C = B - A. Keep a few digits |A| = 8 m/s theta(A) = 45 degrees |B| = 4 m/s theta(B) = 20 degrees

C = 10.35 m/s at 204.49 degrees counterclockwise from the +x-axis

Add the following two vectors if A + B = C. Keep a few digits |A| = 10 N theta(A) = 30 degrees |B| = 8 N theta(B) = 10 degrees

C = 6.44 N at 83.0 degrees counterclockwise from the +x-axis

Find the magnitude and direction of a vector with the following x- and y- components. Keep a few digits for the result to make sense, but not too many that we're overconfident v(x) = 10 N v(y) = 20 N

Magnitude = 22 N Direction = 63 degrees from the +x-axis

Two students measure the acceleration due to gravity with the results g1 = (9.61 +/- 004) m/s^2 and g2 = (9.4 +/- 0.5) m/s^2. If the accepted value of g is 9.8 m/s^2, which of these two is the "better" measurement: the more precise, or less precise? Explain

Measurements are precise when the values are closer to each other. G1 is the more precise measurement because the error is 0.4 in either direction which is closer than G2, which is 0.5 in either direction

"For every action there's an equal and opposite reaction" most closely resembles: - Newton's First Law - Newton's Second Law - Newton's third law

Newton's third law

Does setting up a best fit line mean "connecting the dots"?

No

Two graduate students measure the strength of an MRI's magnetic field to have the following values: Student A: 4.2 +/- 0.8 T Student B: 5.6 +/- 0.5 T Do the two students agree for the strength of the magnet?

No

Did the theoretical mass (1.958 kg) from the balance fall within the error bars of the experimental mass (0.1114 kg)? If not, do you think your percent error (94.3%) is "close enough"?

No, the theoretical mass did not fall within the error bars of the experimental mass. No, I do not believe the percent error is close enough because the percent error was 94.3% which is a very high value for percent error. This shows that there were many errors during the experiment

If I want to compare values before and after an event, I would use: - Percent Error - Percent Difference - Percent Change

Percent Change

If I want to compare predicted results to my measured results, I would use: - Percent Error - Percent Change - Percent Difference

Percent Error

If I want to compare two separate values, I would use: - Percent Change - Perfect Difference - Perfect Error

Perfect Difference

Calculate the mean and standard deviation for your measurements of length and width with the different meter sticks. You may do this by hand - OR by programming Excel on the lab computers Short Meterstick: - L: 137 m, 136 m, 135.6 m, 136.5 m, 136.5 m - W: 122 m, 121 m, 122 m, 121.5 m, 122.4 m Long Meterstick: - L: 136.5 m, 136 m, 136.5 m, 135.7 m, 137 m - W: 121.5 m, 122 m, 120.5 m, 121 m, 121.7 m

Short Meterstick: - L: mean = 136.3; dev = 0.570 - W: mean = 121.76; dev = 0.513 Long Meterstick: - L: mean = 136.34; dev = 0.502 - W: mean = 121.34; dev = 0.59

Even though we are pulling through the same 80 cm, the work done differs as the angle increases. Offer an explanation for the value of the work with increasing angle

The equation for work is W = Fd and the force on it comes from the equation F(A) = Fcos(theta). The angle affects the force which in turn affects the work. This means as the angle increases, the value of cos(theta) decreases, so the value of work decreases

Serving aboard a starship with a Vulcan helmsman means you hear a lot of things like, "At our current velocity we'll reach the planet in 8 hours, 43 minutes, 25.64 seconds." Describe why the feathers on top of your Aurelian captain's head puff up (indicating agitation) whenever she receives these status reports

The feathers on top of the captain's head probably puffed up because an exact value was used to give him his data reports

Time for the lab coordinator exists in five-minute increments, even though his clock has precision to the nearest minute. If, for example, his clock reads 2:38, 2:39, 2:40, 2:41, or 2:42 and you ask for the time, he will always respond "twenty til." Only three significant digits doesn't look like "absorb precision," so why can't you get a more exact answer out of him? Consider what would happen if you asked the coordinator and your TA for the time

The lab coordinate wants a rounded answer instead of an exact time to be given to him

Do resultant vectors depend on the absolute coordinates? That is, is this situation fundamentally different from Unequal Forces in 2-D? What effect does changing the coordinates have on the relative difference in angle between F1, F2, and F3? Explain your answer

The resultant vectors do depend on the coordinates because vectors are made up of direction and magnitude so if you change the coordinate it can change the vector. The coordinates are changed based on the angle because the direction changes; however, the value should be the same because equally changing the angle doesn't change the amount of force

Are the two cylinders made from the same material? Justify your answer and cite evidence from the weight densities. What is a "good enough" tolerance to consider these the same?

These materials were made from different materials. The weight density has a very high difference. If it were the same material no matter the size the weight density would have been the same, but because there is such a stark difference in the weight densities it has to be different materials

We've learned that units are an important indicator not only of the amount of stuff you have, but also an implicit indicator of the nature of the stuff itself. If the units don't match the quantity being measured, (I'm 72 minutes tall, for example), the situation is nonsense. A nonsensical situation would be for me to wad up a $20 note and force it into my car's fuel tank with a ramrod, yet if I say, "I put $20 in the tank last weekend," you seem to know what I'm talking about. How is it that you can intuitively make sense out of a ridiculous mismatch of units such as these?

These units make sense to me because I know that you pay a price per gallon that you put in your tank. This means to me that you used $20 to pay a certain amount of gas to fill your car

The instrument uncertainty for recording the height is 1/2 of the least-count of the meterstick, in this case 0.0005 m. Is this a reasonable estimate of the uncertainty in the heights you measured? Why may this be a gross underestimate?

This is a reasonable estimate because the meterstick does not have the smallest possible value that can be measured visible so there is some uncertainty in the measurement because you cannot be the most accurate from the meterstick. This could be a gross underestimate because the meter is limited in the values shown so this estimate could be greater

Whenever I visit one of the big membership-driven bulk wholesalers in town, without fail I end up using a junk cart with bum wheels that not only drag, but pull to the left. If a cart requires 20 lb of force forward to overcome the wheel's drag, but there are also around 3 lb of force pulling it to the left, with what force and in what direction do I need to push in order to make the cart go forward? Measure your angle from the forward direction and specify whether it's to the left or right. (Be careful in whether a sin or cos corresponds to certain components)

To move the cart with the drag you would need 20.22 lbs of force at an angle of 8.53 degrees

Think critically about what it means to be a component of a vector and the reasoning behind why the two components must be at 90 degrees to one another. Why can't we break a vector into "components" that are 60 degrees apart? We said we could choose any coordinate system we want

Two components must be 90 degrees to one another because it is a part of the trigonometry used to solve for the components. They must be this distance to be able to have an equal balance because if they are not balanced correctly the net force would not be zero

Find the percent error in your angle measurement. Working with angles is tricky because an angle is a relative thing, not an absolute. The following formula respects the relative nature of angle calculations: % error = |(theta(3measured)) - ((theta(3predicted))| / ((theta(3)) - (theta(2)))) x 100%

Using the x-component and y-component of force 3 that I found, I then used the tangent of the components to find the angle. I then added my angle plus 180 degrees to place it in the correct coordinate plane. I then found the percent error from the equation given

Calculate the volume, weight, and weight density for the golden metal cylinder D = 0.01523 m L = 0.05021 m M = 0.0845 kg

V = 9.15x10^-6 m^3 W = 0.8281 N WD = 90502 N/m^3

Were the two forces involved in balancing the washer in the center of the table truly equal? If you had to use a "correction mass," offer an explanation of why "unbalanced" forces resulted in a net force of zero

We did need to use a correction mass during the experiment. The unbalanced forces result in a net force of zero because the system was not perfect. There could be errors in the pulley, how the weight is sitting, how long the ropes of the pulley are, etc. The forces would have resulted in a net balance of 0 if these errors were to be eliminated, but to understand that if perfect we could create a net balance of zero

Were you able to balance the system without using a "correction mass"? How well did the final location of F3 match what you predicted? If they did not, offer an explanation of why it was slightly off

We did need to use a correction mass for our force 3, but we did not need to use a large amount to make these corrections. These corrections were very close to what we had predicted. I think this is because we were predicting for a perfect system when this one did have some errors in it

Total energy is conserved in all cases. Some fraction of the energy you put into the system in the form of work did not end up stored as potential energy. Where did it go?

We know because of the Law of Conservation of Energy that energy cannot be created or destroyed so the energy that is not stored as potential energy could have created heat because of friction

This arrangement is called an Atwood's Machine. When you moved the washer off-center, what did it do? If it stayed in place but was not centered on the table, are the two force vectors still balanced?

When we moved the washer off center, the machine would try and balance the washers in the center but since it was not an equal amount of force it would be pulled toward the side with the greater force because the vector forces had not yet been balanced out

Did this arrangement balance without a "correction mass" with F3 in the location you expected? If not, offer an explanation

Without adding the correction mass, force 3 was generally in the direction we believed that it should have been and we only needed to make small adjustments and our angles were not far off from what the predicted angle would be

You conduct an experiment like we did in lab to measure the mass of a textbook to be 1.312 +/- 0.007 kg. If Sarah measured it with a balance and obtained 1.318 kg, do these two measurements agree?

Yes

You measured the length, diameter and mass of two different cylinders. In both cases, you found that the length had 3 significant figures and that length was the measurement with the fewest number of significant digits. If you found the weight densities to be 38108 N/m^3 and 38061 N/m^3 and you round these values to the correct number of significant figures, can you conclude the two cylinders are made of the same material (do they have the same weight density)?

Yes

If a bus you are riding is traveling at a constant speed and then stops suddenly, you feel "thrown" forward. Which of the following is true at the instant the bus begins to stop? Assume the seat is frictionless and that you are not wearing a seatbelt - You slide forward on the frictionless seat at the same velocity that the bus was traveling prior to the stop - A force is throwing you forward - You are accelerating (remember, there is acceleration when velocities are changing)

You slide forward on the frictionless seat at the same velocity that the bus was traveling prior to the stop

A light ball collides head-on with a stationary heavy target elastically. The ball: - bounces backward - continues forward - comes to a stop

bounces backward

In MKS units, final answers of mass should always be given in which of the following units? - grams - kilograms - pounds - ounces

kilograms

You measure the masses of four bricks to be: {3.4 kg, 3.5 kg, 3.6 kg, 4.2 kg}. What is the mean and standard deviation?

mean = 3.675 deviation = 0.3594

We will need to plot a graph after taking your force and acceleration data. Correctly set up and label the axes of this graph - Acceleration - Force - Force vs. Acceleration - m/s/s - N

title: Force vs. Acceleration x-axis: Acceleration; units: m/s/s y-axis: Force; units: N

You perform an experiment in slacking off at work by clocking out earlier each week and seeing how it affects your paycheck. Properly title the graph and label the axes for the plot your collected data. Think about independent and dependent variables. Which one corresponds to the variable you changed directly? - hours - Pay Received - Pay Received vs. Time Worked - Time Worked - $

title: Pay Received vs. Time Worked x-axis: Time Worked; units: hours y-axis: Pay Received; units: $

Break this vector into x- and y- components. v = 15 N theta = 30 degrees

v(x) = 13 N v(y) = 7.5 N

Suppose we want to linearize by substitution the formula for dependent variable Kinetic Energy (K) with independent variable velocity (v). If the original equation is K = (1/2)mv^2, what will our "new" independent variable (x) be when we "map" this onto y = mx + b? - (1/2)m - K - v^2 - v

v^2

How many significant digits are in this number? 2800

2

If gas costs $2.56 per gallon, and it takes 21 seconds to pump one gallon of gas, how long will it take to pump $23.81 worth of gas (in seconds)?

195.32

Using the unrounded volumes, calculate the percent error for all three cases. Assume 37,500 cm^3 is the theoretical volume, while the three volumes with "tweaked dimensions" are all measured. You should now round your percent errors to correct significant digits. Tweaked dimensions: 1. 37,512.5 cm^3 2. 37,537.5 cm^3 3. 37,875 cm^3

1. 0.0333% 2. 0.100% 3. 1.00%

Using the rounded volumes, calculate the percent error for all three cases. Use 37,500 cm^3 as your theoretical value 1. 38,000 cm^3 2. 38,000 cm^3 3. 37,900 cm^3

1. 1.3% 2. 1.3% 3. 1.07%

The instrument device has an error bar of 0.05 cm. Recalculate the volume of the tabletop three times - adding 0.05 cm to each of the dimensions (combinations listed below). 1. L = 150.05 cm; W = 50.0 cm; H = 5.0 cm 2. L = 150.0 cm; W = 50.05 cm; H = 5.0 cm 3. L = 150.0 cm; W = 50.0 cm; H = 5.05 cm

1. 37,512.5 cm^3; 38,000 cm^3 2. 37,537.5 cm^3; 38,000 cm^3 3. 37,875 cm^3; 37,900 cm^3

Calculate the potential energy stored in a cart of mass 502.4 g elevated to a height of 26.07 cm. Your result should be reported in Joules

1.28

Calculate the volume of the white metal cylinder. The formula for the volume of a cylinder is given by V = (pi/4)D^2L D = 0.01561 m L = 0.07098 m

1.36x10^-5 m^3

Calculate the work done on the sled by your applied force on the incline d = 80 cm F = 1.848 N

1.4784 J

Compute the total mass of the sled + three added masses - Sled: 0.1765 kg - Mass 1: 0.5005 kg - Mass 2: 0.5007 kg - Mass 3: 0.501 kg

1.6787 kg

Sum the three masses to find the total mass experiencing acceleration in the experiment - Cart: 0.0538 kg - Force Sensor: 0.092 kg - Steel Weight: 0.5 kg

1.958 kg (theoretical mass)

Recall that weight is a force and is equal to m*g, where g is the acceleration due to gravity exerted by the Earth near the Earth's surface. The acceleration due to gravity exerted by the moon near the moon's surface is 16.6% that of Earth. What is the weight (in N) of a person with a mass of 63.6 kg on the moon?

103.46

Compute the percent difference in the weight density from the white to the golden cylinder WD(white) = 27382 N/m^3 WD(golden) = 90502 N/m^3

107%

Calculate the weight density of the plastic object. Recall that Density = weight/Volume Weight = 0.6865 N Volume = 5.96x10^-5 m^3

11519.5 N/m^3

A car moving at some speed hits the brakes and skids to a stop after 13 m on a level road. If the coefficient of friction for the road conditions of dry concrete is 0.60, what was the car's original speed (in m/s) before braking?

12.36

Momentum is defined as mass times velocity. You find the mass of a car to be 2123.6 kg and the velocity of the car to be 7.1 m/s, giving you a momentum of 15077.56 kg-m/s. Round this momentum to the correct number of significant digits

15000 kg-m/s

Calculate the area of the lab table from the "better" length and width average. Remember significant digits and recall that A = LW L = 136.34 W = 121.34

16543 m^2

Calculate the spring constant, k, if the spring is compressed by 1.00 cm and the total stored potential energy is 0.00842 J. Your answer should be in N/m or kg/s^2

168.4

A fighter pilot is exposed to an acceleration of 3g in the horizontal direction during takeoff. Knowing that 1g = 9.8 m/s^2 and that the mass of the fighter pilot is 64.1 kg, what force (in Newtons) does the fighter pilot experience in the horizontal direction? This is the force that she feels "pressing her into the back of the seat"

1884.54

On a microscopic level, muscle contractions operate under a mechanism where big bulbous heads of a myosin filament bond to an actin filament, then those myosin heads bend to propel the myosin filament forward. After this "power stroke," the myosin head detaches, reaches forward and reattaches further along the actin filament to repeat the process. Imagine yourself with a hundred myosin arms climbing up an actin rope in gym class. Holding a heavy book stationary with your arm extended straight out does no work (because the distance d for your supporting force is zero); yet you will begin to fatigue after a minute, implying energy is being lost. Propose a hypothesis as to why your energy reserve is being expended with consideration given to Work = Fd, the microscopic mechanism for muscle action, and any other concepts you learned about work and energy from this lab

Even though there is no work being done, the body uses energy to hold the book. The book has weight and gravitational force pulling down on it. The actin-myosin complex is used in stretching muscles in order to hold up the book. Energy is lost through the myosin head detaching and then reaching forward to reattach further down the actin filament to then repeat the process. This and the stress on the body which uses energy by sending chemical signals through the body causes the loss of energy and the feeling of fatigue

True or false? The bumper at the end of the track is durable enough to stop the cart and you should not touch the cart at all after it is release

False

You had to make a choice between the short meterstick and the long meterstick for the best length and width measurements. Why did you choose the results you did? Compare the statistical uncertainty (standard deviation) of each meterstick. If they are not the same, offer an explanation for the improved precision

I chose the long meter stick because I did not have to move it to find my measurements. The standard deviations were similar for both so I trusted the long meter stick more because I was able to just put it down and look for the measurement. The short meter stick required me to move it to get the total distance. This could lead to error if I did not put it back in the correct spot and continue measuring

In all three cases, we applied the same 0.05 cm worth of uncertainty. In which of those cases did it make the most and least difference in the net volume's error? Offer an explanation as to why 0.05 cm makes a difference along those diameters

I found that the value of error in length has the least difference in the net volume, and I believe this is because it is the greatest value so a small change does not have as big of an impact. I also found that the value of error in height had the most difference in net volume because it was the smallest value so a change in its value has a greater impact on the net volume

You were explicitly told not to round one set of data until the final calculation was complete. Compare your volumes and percent errors between the unrounded and pre-rounded sets. What do you notice? Offer some insights into what you've observed and explain which method is better

I observed that the percent error was smaller for the unrounded values than the rounded values. I think that this is because the unrounded values were closer to the perfect value or the theoretical value

Using the known Forces 1 & 2, predict the required Force 3 in order to bring the system into balance (Hint: if F1 + F2 + F3 = 0, how do you find F3?). Break F1 and F2 into x- and y-components. Put appropriate +/- signs on them, sum, and find the appropriate components of a third F3 required to make the resultant zero. Express this F3 with its components, magnitude, angle, and corresponding mass. Note: if we trust the masses to be made correctly by the manufacturer, simply round your final predicted F3 to the same number of significant digits as F1 and F2. Keep five decimal places for the x- and y-components to prevent roundoff error early in the problem

I predicted for force 3 that the total mass would be the same as the other masses. I then added together the x-components of force 1 and force 2 and the new total force needed to equal 0 so I set the combined x-components + force 3 equal to 0 and subtracted to get my x-component and y-component for force 3. I repeated this step using the data from the y-components. I added the x-component and y-component of force 3 that I had calculated to get the total of force 3

Covert the two masses into a corresponding weight (a force) and find the resultant vector of the two forces. Because the system is one-dimensional, the individual vectors have already broken themselves up into components. If you don't see it, do your sines and cosines to be sure

In the equal forces in 1-D section, after I created the equilibrium and found the force 2 by using the force formula of F=ma, I was able to calculate that F2 = 1.49

In this lab (and others) we will be doing calculations with the gravitational constant g = 9.8 m/s^2. Because we will treat it as a mathematical constant assumed to be known exactly, how many significant digits does it contain? - 1 - 9.8 - 0.1 - Infinite digits of precision and infinite significant digits - 2

Infinite digits of precision and infinite significant digits

Carefully consider your means and standard deviations. Make a judgement call between the data for the short meterstick and the long meterstick when choosing which set of measurements is more appropriate to use, long or short. Think about which tool gave you a "better measurement."

Long Meterstick