Question
Hello, I have a lab after tomorrow, and I am very bad at physics. I want to prepare myself for the lab since it's hard and long. Pictures 1 - 3 , are explanations of the lab, 4 - 6 are the lab that we're assigned to do. I prefer that you print out the lab paper (fourth & fifth & sixth page). and then take a picture of them.
There will be a lot of measurments and stuff like that. But I want you to put random numbers in each column (assuming you have equiment in front of you) and then explain how you answered that (if there was a formula or something). You can do one row only , so I can get the idea only.
Try to answer questions 1 - 6 briefly. ( in the last two pages )
This is really hard for me. I really need your help. i just want to get the idea of the lab.
Thanks
OBJECTIVE You will investigate some ol the properties of a spring in order to learn the correct way to express data in graphic form. You will also learn how to analyze the graph. EQUIPMENT Spring, meter stick, set of masses, stopwatch, spring stand THEORY How to make graphs 1. Always use graph paper. Use a full page for each graph. 2. Identify the independent and dependent variables. The independent variable is the quantity whose values you get to choose during the experiment. It is usually plotted on the horizontal axis. The dependent variable is the quantity that changes due to changes in the independent variable. The dependent variable is usually plotted on the vertical axis. In this experiment, you will change the mass hanging on a spring and measure the amount that the spring stretches. Hence the mass is the independent variable and the stretch is the dependent variable. 3. Scale each of the axes. Examine the range of values for both variables. Label each axis in such a way that all data values will fit on the page. Do not extend the scale of the axis tar beyond the range of values to be plotted. Do not include the origin unless it is in or near the range of values to be plotted. Label the axes in sensible divisions (for example, in increments ot 2, 10, or 0.1; not 0.23 or 17). Write the variable name and its units along each axis. Refer to Fig. 1. The best fit line has a slope given by: The y-intercept is then given by: Where: Suspend the spring from the stand. Measure the rest position of the end of the spring with a meter stick, xQ. Repeat the position measurement when varying masses arc hung on the spring, Xf. Make sure your measurements are all of the same point on the spring. Measure the length for ten different masses, none greater than one kilogram. Make all measurements in centimeters and grams, and include uncertainties. Can your data be fit well by a straight line? Explain What is the slope of your graph of stretch vs. mass? Part II. Oscillations When a mass is hung from a spring it tends to oscillate. How does the period of oscillation depend on the mass? This can be answered by measuring the perio- o. oscillation for various masses. The period is the time needed for one comp ete oscillation cycle. The equation describing this motion is: T2 = 4pie2m/k Where m is the mass on the spring and k is the spring constant. Using a stopwatch, measure the time for ten oscillations which is ten times the oscillation period. Record the oscillation period for eight different masses; no greater than 500g. Calculate the average time Make a graph of T2 vs. m. Draw the best straight line "eyeball" fit to each graph. N.B. In the third part of the physics series, we will explore this kind of oscillation, called simple harmonic motion, in much greater detail. What is the slope of your graph of T2vs.m? What is your spring constant? What are sources of error for this experiment?
Explanation / Answer
This is not a very difficult experiment. So relax!
All you require is the Hooke's law, which states
F = - kx
where F is the force applied
k is the spring constant of the spring used
x is the elongation
For the 1st table, I DO NOT KNOW the spring constant of the spring in your lab.
I will assume it to be = 10 N/m
hence these will be good readings..
1. mass = 10 g , x0 = 10 cm, xf = 11 cm, x = 1 cm
2. mass = 20 g , x0 = 10 cm, xf = 12 cm, x = 2 cm
3. mass = 30 g , x0 = 10 cm, xf = 13 cm, x = 3 cm
Just make sure Hooke's law is satisfied. DO NOT ADD A LOT OF WEIGHT.
1 >> Yes the data can be fit well by a staright line because the elogation has linear dependency on the force applied.
2>> slope = 1/ 10 = 0.1 cm/g
3>> the error in observation of time required to make a certain number of oscillations is inversely proportional to the root
of the number of oscillations.
Hence the more the number of oscillations, the better the accuracy.
Hence 10 oscillations instead of 1.
This is the model 2nd observation table.
1. mass = 50g, 10T = 140 s
2. mass = 100g, 10T = 197 s
3. mass = 150g, 10T = 245 s
4>> slope = 14^2 / 50 = 3.92
5>> spring constant = 4 pi^2 / slope
= 10.07 <----- This should be finally as close as possible to the one in your lab. I had taken 10 here and I got very close to it
6>> 1. human error includes noting time period incorrectly
2. the spring is not MASSLESS
3. there is friction between the spring and the point from which it hangs.
