PHYSICS LAB FINAL 2108

What is the least-count of the ruler? Answer 0.1

(b) From the picture, what is the measured value? Answer 10.7

A 11600 kg railroad car is coasting on a level, frictionless track at a speed of 16.0 m/s when a 5420 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.

10.9 m/s Change in KE: ___% m1*v1 + m2*v2 = (m1+m2)*V 12100*19 + (4790*0) = (12100+4790)*V V = 13.61 m/s <---------answer KE1 = 0.5*m1*v1^2 = 0.5*12100*19*19 = 2184050 J KE2 = 0.5*(m1+m2)*V^2 = 0.5*(12100+4790)*13.61*13.61 KE2 = 1564285.0845 J % change = K2-K1/K1 = (1564285.0845 - 2184050)*100/2184050 = 28.3 %

Calculate the work done on a cart (in Joules) by pulling it a distance of 103.8 cm with a force of 10.71 N parallel to the direction of travel.

11.1 (Fdcostheta)

how close it is to the center of the board

Accuracy

Add the vectors A+B=C |A|=15 N 20 degress |B|= 11N 40 degrees

C = 13.5 N at 65.2 degrees CCW

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 released.

False

In this lab (and others) we will be doing calculations with the gravitational constant g = 9.8 m/s2. Because we will treat it as a mathematical constant assumed to be known exactly, how many significant digits does it contain?

Infinite digits of precision and infinite significant digits

If the amplitude setting on the function generator is set too high, which of the following is true?

It will be indicated by a pounding sound. The amplitude should be lowered immediately

A heavy ball collides head-on with a stationary light target elastically. The ball:

continues forward

Calculate the potential energy stored in a cart of mass 489.3 g elevated to a height of 29.30 cm. You result should be reported in Joules.

1.4 Potential energy stored= mgh= 0.544*9.8*0.2163= 1.15J

How many consecutive periods will you measure for each run in the Simple Harmonic Motion experiment?

20

When you are finished with the non-water liquid (liquid X), you should pour it down the sink.

False

LAB 6:

Inclinometer Correct Photogates Correct Triple Beam Balance Correct

What are the units of k?

N/m

"For every action there's an equal and opposite reaction" most closely resembles:

Newton's 3rd Law

2 graduate students measure the strength of an MRI's magnetic field to have the following value: Student A: 4.2 +- .8 T Student B: 5.6 +- .5 T Do the 2 students agree for the strength of the magnetic field?

No

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

No

If I want to compare values before and after an event, I would use...

Percent Change

If we create a plot of wavelength vs inverse frequency, what will the value of the slope of a linear best fit line be equal to in terms of the tension of the string, T, and the linear mass density of the string, μ?

Sq-rt (T/mu)

You should never remove the cradle and link wires from the triple beam balance at any point during this lab.

True

You should unhook the alligator clip before you add additional mass to the mass hanger and reattach the clip afterward.

True

Which of the following are valid reasons to take multiple measurements?

You are gaining accuracy. You generally end up with a result closer to the true value.

INSTRUMENTS FOR LAB 4

a. Triple-beam balance Correct c. Force sensor Correct e. Inclinometer Correct

What instruments will you be using this week? LAB 7

b. Triple-beam balance Correct c. Mass Hanger Pan Correct e. Photogate Correct

In a new lab experiment, you find the spring constant of a "good" and "bad" spring. The "bad" spring is exactly the same as the "good" spring, except that it has been permanently deformed by misuse. If you find the "good" spring to have a spring constant of 8.81 N/m and the "bad" spring to have a spring constant of 4.34 N/m, what was the percent change in the spring constant caused by deforming the spring?

bad-good/good = -

What do vectors have

direction and magnitude

The magnitude of the force a fluid exerts upward on an object is AnswerCorrect the magnitude of the weight of the fluid displaced by the object.

equal to

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 = 10N **vx cos {v}_y = 20N

magnitude: 22.36 so square root vvx^2 +vy^2 direction: 63.43 tan inverse xy/vx

You measure the masses of five bricks to be: {3.2 kg, 3.5 kg, 3.4 kg, 3.8 kg, 5.5 kg}. What is the mean and standard deviation?

mean: 3.9 deviation: .93: Press [2nd][LIST] • Scroll to MATH and select 7:stdDev(

LAB 3: What instruments will you use this week?

vi. Pulleys Correct vii. Force Table Correct iv. Mass Hanger Pans i. Slotted Masses

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/m3 and 38061 N/m3 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 we create a plot of T2 vs mass, what will the value of the slope of a linear best fit line be equal to?(4pi

(4pi^2)/k

LAB 2 WEEK PRELAB " Which of the following instruments will you be using to make measurements this week in lab?

(Select all that apply.) Select one or more: a. digital caliper Correct b. meter stick Correct c. triple beam balance Correct

Calculate the % change from before to after a collision if Pbefore = 0.172 and Pafter = 0.155.

-9.88 ans= (0.166-0.180)*100/0.180 = -7.78 % absolute value? no

You take a set of measurements for the wavelengths and frequencies of standing waves on a string that is under a tension of 1.49 N. You use your data to create a plot of wavelength (in m) vs inverse frequency (in s) and the linear fit of your graph gives a slope of 19.4. What is the linear mass density of the string in kg/m?

.00396 v = 18.8 sqrt(T/mue) = 18.8 T/mue = 18.8^2 mue = T/18.8^2 = 2.98/18.8^2

Calculate the momentum (in kg-m/s) of a cart with mass 0.4923 kg travelling at a velocity of 0.46 m/s.

.23

Compute the torque (in m-N) applied by a hanging mass of 111.5 g at 37.6 cm away from the axle. The torque is applied perpendicularly to the radius.

.411 Torque = Fperpendicular x R = (Mxg) x R = {(102.5/1000)x9.8}N x (47.6/100)m

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 77.8 kg on the moon?

126.6 9.8 times 16.6/100 F=mg mass (kg times number you got from earlier)

Momentum is defined as mass times velocity. You find the mass of a car to be 2014.88 kg and the velocity of the car to be 7.85 m/s, giving you a momentum of 15816.808 kg-m/s. Round this momentum to the correct number of significant digits.

15800 answer will be given in least significant figures velocity has 2 significant figure only so momentum=14000 kgm/s instead of 14334.612 kg-m/s.

You perform the Simple Harmonic Motion experiment and create a plot of Period-Squared vs. Mass. You add a linear fit and find the following equation of the line: y=8.70x-0.070 What is the spring constant, k (in N/m or kg/s2)?

4.5 solve for slope=4pi^2/k (slope is 8.70)

Using Hooke's Law, you find the spring constant of a given spring to be 7.9 N/m \pm 0.6 N/m. Your lab partner uses simple harmonic motion and finds the spring constant to be 8.9 N/m \pm 0.3 N/m. Would you consider these two springs to have the same spring constant?

No

You conduct an experiment like we did in lab to measure the mass of a textbook to be 1.305 \pm0.008 kg . If Sarah measured it with a balance and obtained 1.290 kg, do these two measurements agree?

No

how close the data points are together

Precision

You are trying to determine the specific gravity of a solid object that sinks in water. If m is the mass of your object and mA is its apparent mass when submerged in water, what is the specific gravity of the substance? Select one: S.G.= \frac{m}{m-m_{A}} Correct

S.G.= {m}/m-m_{A}} Correct

LAB 5 What instruments will you be using this week?

Select one or more: a. Inclinometer Correct b. Force Sensor Correct c. Meterstick Correct . Triple Beam Balance Correct

Calculate the specific gravity of a liquid given the following information: m = 50.44 g, mA = 31.11 g, mL = 43.07 g.

The specific gravity of a liquid is, S = (m - mL)g / (m - mA)g = (53.5 g - 42.0 g)g / (53.5 g - 34.0 g)g = 0.5897 = 0.59 2. The specific gravity of a solid is, S' = mg / (m-mA)g = (24.8 g)d / (24.8 g - 18.0 g)g = 3.647

In this type of wave, the oscillation is perpendicular to the direction of the wave.

Transverse

When you are finished with the water, you should pour the water down the sink.

True

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

LAB 8 What instruments will we be using? (Select all that apply.)

jolly balance Correct stopwatch Correct triple beam balance Correct

An ideal spring should behave ________ in its relationship between force and displacement.

linearly

In general, how should you shuffle the mass in a rotating object to decrease its overall moment of inertia?

move the mass closer to the axis of rotation

How many nodes are in the standing wave pictured? Answer 5 Correct (a) How many antinodes are in the standing wave pictured? Answer 4 Correct *1/f=s (a) What harmonic is the standing wave pictured? 4

nodes middle dot

If the leftover energy in the previous problem is 131.0 J (it's not, don't go back and try to use this value) and the mass is 2 kg, what speed (in m/s) does the block have at the bottom of its slide? Revisit the definition of KE if needed.

root 2E/m

In MKS units, final answers of time should always be given in which of the following units?

s

For this week's experiment, n equals the following.

the number of antinodes in the standing wave the harmonic number of the standing wave

You will collect acceleration data from how many positions for the adjustable masses on the spin-mill?

7

You perform the Hooke's Law experiment and create a plot of Displacement vs. Force. You add a linear fit and find the following equation for the line: y=0.169 x - 0.011 What is the spring constant, k (in N/m or kg/s2)?

5.9 k=1/slope

Force on the bottom of a cylinder submerged in water will be the force on the top.

greater than

You measure a sheet of paper. The width is 8.48 inches and the length is 10.71 inches. What is the area of the paper in MKS units (m2)?

.0586: Area = width*length = 0.215646*0.281686 = 0.0607 m^2

Calculate the kinetic energy (in J) of a cart with mass 0.5025 kg travelling at a velocity of 0.50 m/s.

.063

If a standing wave with 11 antinodes occurs at a frequency of 44.5 Hz, at what frequency would you look for the n = 3 standing wave?

12.1 Hz for 10 antinodes 10 loops forms.. then f10 = 10f1 = 44.1.. then fundamentalfrequency f1 = 44.1/10 = 4.41 Hz.. when n=2 frequency f2 = 2*f1 = 2*4.41 = 8.82 Hz

The spin-mill should be high enough that it collides with the photogate head as it spins.

False

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 0.50, what was the car's original speed (in m/s) before braking?

v = sqrt( 2 μ g S )

Using the pulley system below, if m1=3.5 kg and m2 = 8.4 kg, what is the acceleration of m2 in m/s/s? Use up as the positive direction for m2. Hint: Draw force diagrams. Hint: Derive two equations with two unknowns.

-4.04 m2-m1*9.8/m1+m2 for m2 it's negative

The speed of light is 299,792,458 m/s. However, most physicists round this number to 3x108 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.

.07% percent difference=(300000000-299792458)*100/(300000000)=0.07 percent

"Acceleration depends on force" most closely resembles:

2nd law i think

Calculate the Specific Gravity of an object that sinks in water if m = 24.46 g and mA = 17.33 g.

3.431 m/m-ma

Humans life an average of 84.6 years in Japan. Express this time in units of days if the conversion factor is exactly 365.25 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).

30900

If gas costs $1.74 per gallon, and it takes 21 seconds to pump one gallon of gas, how long will it take to pump $29.44 worth of gas (in seconds)?

355

How mant significant digits are in the number 0.00001980?

4

Find the percentage of the total work lost to friction if 21.5 J of work is put into pushing a block up a ramp resulting in 12.0 J of stored potential energy at the top. Report the percentage lost as a positive number.

44% Total Work done = Energy lost to friction + potential energy stored 26.3 = 11.9+Energy lost ot friction Energy lost to friction = 26.3-11.9 = 14.4 J required percentage is (14.4/26.3)*100 = 54.75 %

If I want to compare two separate values, I would use:

Percent Difference

If I want to compare predicted results to my measured results, I would use:

Percent Error

All waves that cause particles of a material to be disturbed and transfer the disturbance to the neighboring particles by contact are this kind of wave.

mechanical

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)m v^2, what will our "new" independent variable (x) be when we "map" this onto y = mx + b?

v^2

If we create a plot of wavelength vs inverse frequency, what will the value of the y-intercept of a linear best fit line be equal to in terms of the tension of the string, T, and the linear mass density of the string, μ?

0

In lab, you performed an experiment with a spring to find the mass of an "unknown mass." If the spring constant is 9.94 N/m and the "unknown mass" caused a displacement of \Delta 16.1 cm, what is the mass of the "unknown mass" in kg?

0.163 m = k times Delta x/g = 9.32 N/m ( 0.172 m)/ 9.8 m/s^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/s2

168 E= 1/2 K X2

A fighter pilot is exposed to an acceleration of 3g in the horizontal direction during takeoff. Knowing that 1g=9.8 m/s2 and that the mass of the fighter pilot is 63.1 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."

1855 F=ma 3mg

To leave Nicholson, you exit via the door to the quad. The door is 40 inches wide and has a mass of 200 kg. You push the door with a perpendicular force of 51.43N exactly 0.89m away from the hinge. This generates the minimum torque, \tau_1, required to open the door. If you pushed the door 0.24m away from the hinge, with what force (in N) must you push the door to supply the same torque?

191 T = force * distance Now , for equating torque in both cases F*0.16 = 47.78 * 0.88

The known area of a table is 1.50 m2. You measure the length of the table to be 1.30 m and the width to be 1.18 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?

2.27

You are swinging a yo-yo around in a circle above your head. Assume this is a perfect system: the mass of the string is negligible, the yo-yo is a point mass and your arm is a perfectly vertical axis of rotation. Given the mass of the yo-yo is m and the length of the string (radius of the circle traced by the yo-yo) is L, you find the moment of inertia to be I. If you double the length of the string, what is the new moment of inertia? Hint: Consider the equation for moment of inertia of a point mass about an axis in your lab manual.

4 I

A billiard ball with mass 9.3 kg is shot due west at 4.2 m/s. The ball collides elastically with a second billiard ball, also of mass 9.3 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?

4.2 2m1/m1+m2 times vo1

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 50.7 Gy +/-2.00%, what is the maximum dose the patient can receive (in Gy)? Note: A Gy is measure of the amount of energy deposited per unit mass.

51.7 55.5*.02=1.11 55.5+1.11=56.61

Your friend weighs 144.1 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)

65.40

In figure skating, a triple Axel is a jump in which the figure skater leaps into the air while facing forward, performs 3.5 revolutions, and then lands facing backwards. During the spin, the skater hugs his/her arms close to the body. Choose the answer that best explains WHY the figure skater does this. Think about the experiment you performed on the rotating stool.

Due to conservation of angular momentum, decreasing the effective radius of the figure skater by pulling in the arms increases the angular velocity of the figure skater. This allows the figure skater to spin faster in the air to fully complete the triple Axel.

LAB 9 What instruments will be used this week? (Select all that apply.)

Select one or more: mechanical vibrator Correct electronic function generator Correct string Correct

What is the acceleration of either block in the pulley example on page 4-2 with the given free body diagrams?

\frac{(M_1 - M_2)}{(M_1+M_2)} g Correct

Imagine you have a system of two buckets as shown below. The buckets are spinning about an axle with frictionless bearings at some angular velocity, \omega. It starts to rain. What happens to the two-bucket system? Think about angular momentum

a. \omega must decrease to conserve angular momentum because because the rain increases the mass of the system (which increases the moment of inertia). Correct

A block of mass m begins at rest at the top of a ramp at elevation h with whatever PE is associated with that height. The block slides down the ramp over a distance d until it reaches the bottom of the ramp. How much of its original total energy (in J) survives as KE when it reaches the ground? (In other words, the acceleration is not zero like it was in lab and friction does not remove 100% of the original PE. How much of that original energy is left over after the friction does work to remove some?)

ef=mgh Eloss =umgcosthetad ef-eloss

In an elastic collision, which are conserved?

Kinetic Energy and momentum

Sound is this type of wave.

Longitudinal

A light ball collides head-on with a stationary heavy target elastically. The ball:

bounces backwards

The upwards force on a submerged object is called a AnswerCorrect force

buoyant