141 Lab Final

Question 1

Do significant figures count zeros before the number?

Answer 1

no

Question 2

How many sig figs can you record on an instrument like a ruler?

Answer 2

as many numbers can be read on the ruler PLUS ONE estimated number

Question 3

When are trailing zeros significant?

Answer 3

only if the decimal point is shown

Question 4

How many significant figures in 0.00334?

Answer 4

3

Question 5

How many significant figures in 1.3800 × 10^4?

Answer 5

5

Question 6

How many significant figures in 34.00?

Answer 6

4

Question 7

When multiplying or dividing numbers, what should be the number of sig figs?

Answer 7

the number of significant figures equals the smallest number of significant figures in any of the original numbers

Question 8

8.3 m × 1045 N equals what?

Answer 8

8700 Nm (not 8673.5 Nm)

Question 9

What do axis labels on Excel graphs need to include?

Answer 9

the units in parentheses

Question 10

What should be displayed on graph?

Answer 10

equation and R2

Question 11

What does every reported value need?

Answer 11

an uncertainity measurement

Question 12

How many digits should uncertainity be rounded to?

Answer 12

uncertainity should be rounded to 1 sig fig

Question 13

How should uncertainty and the measurement be the same?

Answer 13

uncertainty and the measurement should be rounded to the same decimal place

Question 14

How do we eliminate the systematic error from the camera’s shutter in tracker?

Answer 14

turn the video horizontally

Question 15

When using the hop frog method to calculate velocity where should you not have a value?

Answer 15

the first and last cells in the column

Question 16

In projectile motion, what is true of velocity and acceleration in the x-direction?

Answer 16

Acceleration is 0, so velocity should be constant in the x-direction

Question 17

How can you eliminate the systematic error from the camera’s shutter in projectile motion?

Answer 17

use a matched data set

use equal number of data points on the uptrip and downtrip whenever graphing

Question 18

What should you do to times from tracker?

Answer 18

re-zero the times so that zero is included on the x-axis of a “versus time” graph

Question 19

When the glider is moving to the left what do you want to do to the axis in tracker? (like in the gliding mass)

Answer 19

You want to call the leftwards direction positive to get positive values

Have to click-and-drag the vertical tick-mark on the axis 180º

Then, move axis to the lower right-hand corner

Question 20

What do you always need to do in tracker?

Answer 20

1) Set your reference measurement

2) Set your axis so that you get positive values

Question 21

In lab 4 (with the gliders), explain what the slope of Fnet versus M2 equals?

Answer 21

The slope of Fnet versus M2 equals gravity (g)

Since our force equation is Fnet=gM2, if we treat this like y=mx+b our slope is gravity

Question 22

How did we find Fnet as a function of M2 in lab 4 (with the gliders)?

Answer 22

We calculated individual accelerations for varying amounts of added weight

Then we used the acceleration*total mass to generate Fnet

Then, we have Fnet as a function of M2

Question 23

How to find kinetic energy of the pendulum?

Answer 23

first, need to find the speed (v) which is going to be a combination of x and y components

find the distance between the two successive points using “s=” formula and then divide by the time between two points (we used 0.0333 seconds in lab)

Question 24

When calculating the distance between two points (like with the pendulum) which cells will not be filled?

Answer 24

the first cell will NOT be filled, but the last cell will be filled

Question 25

What is the first step we do to measure potential energy in the pendulum?

Answer 25

set the height at the bottom of the swing to equal 0

this allows us to have potential energy=0 at the bottom of the swing

do this by finding the y-coordinate at the lowest point of your tracker measurements

Question 26

What do we do in excel to measure potential energy of the pendulum?

Answer 26

use the “h=” formula and create a new column adjusted for height

then multiply this column by mg

*this column will be empty at the first cell

Question 27

What does the y-intercept of a v^2 versus h graph tell us? (pendulum)

Answer 27

the velocity at the bottom of the swing

can multiply by 1/2*m to get the kinetic energy

since h=0, we know we have all kinetic energy and no potential energy

therefore, the kinetic energy at the y-intercept equals the total energy of the system

Question 28

What does the x-intercept of a v^2 versus h graph tell us? (pendulum)

Answer 28

the release height/the maximum height

there is no velocity, so we know that we are at the maximum height/all energy is equal to potential energy

Question 29

What was the point of the circular motion lab?

Answer 29

to prove that although the puck’s speed doesn’t change, it is accelerating because it’s direction changes

Question 30

Centripetal (radial) acceleration

Answer 30

points towards the center of the circle

due to velocity changing directions not magnitude

caused by familiar forces

always have centripetal acceleration when moving in a circle

Question 31

Difference between angular and centripetal acceleration

Answer 31

angular acceleration is an angular quantity whereas centripetal acceleration is a linear quantity (m/s2)

angular acceleration just refers to if angular velocity is slowing down or speeding up

can be rotating without an angular acceleration (magnitude not changing)

Question 32

What do you need to find for centripetal acceleration?

Answer 32

it is a vector quantity, so need to know magnitude and direction

Question 33

What is the first step of finding centripetal acceleration using the paper circle?

Answer 33

measure the distance between a couple of points and divide by 0.00333 seconds (the amount of time between each)

average these velocities together to get a single constant velocity

Question 34

Translating final and initial velocities on paper circle?

Answer 34

the final and initial velocities should be the same length

translate the final velocity to the initial velocity TAIL to TAIL

measure the change in velocity between final and initial (vf= vi + ∆v)

∆v should be tip to tail with vi (∆v has tail at the head of vi)

Question 35

What is the final step in finding the centripetal/radial acceleration using the paper circle?

Answer 35

divide the found ∆v by the ∆t between vf and vi

Question 36

What is an alternate way to find centripetal/radial acceleration using the paper circle?

Answer 36

use the formula a=v^2/R

square the first found, constant velocity and divide by the radius of the circle

Question 37

Why do you get more torque further from the hinge?

Answer 37

bigger distance the torque can act through

Question 38

Archimedes principle

Answer 38

bouyant force is equal to the weight of the displaced force

Question 39

What happens if an object’s weight is greater than the weight of the fluid displaced?

Answer 39

the object will sink

the object’s weight is greater than the bouyant force

Question 40

What happens if an object’s weight is less than the weight of the fluid displaced?

Answer 40

the object will float

the bouyant force is greater than the weight and the object floats

Question 41

What force does a scale most directly read?

Answer 41

the normal force

or tension if the scale is hanging

Question 42

How do you find the volume of an object submerged underwater?

Answer 42

use a force diagram and equations for the bouyant force (these are written down)

Question 43

How do you find the density of an object submerged underwater?

Answer 43

first, find the mass from the scale reading of weight outside water (divide by gravity)

then, use a force diagram to solve for the volume using buoyant force

Question 44

Simple harmonic motion

Answer 44

Results when an object is subject to forces which give it an acceleration proportional to its displacement from its equilibrium position

Question 45

Graph of applied force (newtons) versus elongation (meters)

Answer 45

Slope tells us the spring constant in N/m

Question 46

How do you change the applied force on a spring to graph applied force as a function of elongation?

Answer 46

Change the weight hanging from the spring

This will change the applied force (gravity)

Question 47

Does period depend on amplitude? How do we experimentally prove this?

Answer 47

No! Can prove this by changing the release amplitude and measuring the period

The period will not change

Question 48

Does period depend on applied force/added mass?

Answer 48

yes

Question 49

Graph of period (in s^2) versus mass (kg)

Answer 49

another way to calculate a spring constant through slope

need to rearrange a formula to calculate (formula is written down)

generate this graph by measuring the period of different applied forces/ added mass

Question 50

How to find a spring’s effective vibrating mass?

Answer 50

should be the “negative” mass on the x-intercept of a s^2 versus kg graph

Question 51

How many sig figs based on a graph?

Answer 51

if using the slope and/or the y-intercept use 3 sig figs based off of a graph

Question 52

What do excel trig functions automatically calculate in?

Answer 52

radians

need to use formula if importing degrees

Question 53

What should be the same in lab one?

Answer 53

the average of the calculated velocities and the slope of position versus time graph

since velocity is constant in lab 1

Question 54

How many points do you count from between the two vectors on the circle to determine ∆t?

Answer 54

??? Figure out