Physics 1050L
Consider the following assumption made by the students:"The amount of coffee grounds was measured accurately before adding them to the soil."
Although inaccurate measurements might impact the results of the experiment, this is not considered an appropriate assumption to report.
What did the researchers conclude (choose the best possible answer):
For every hour of television watched after age 25 it shortens the viewer's life expectancy by 21.8 minutes.
The results of the study (choose one):
Supported the hypothesis.
Consider this graph which shows carbon dioxide levels that were measured each January over five decades at the Mauna Loa observatory in Hawaii. What is a possible hypothesis for the investigation portrayed in this scenario
The amount of atmospheric carbon dioxide is related to the year it was measured.
Consider an ice skater spinning in place with both skates close together. At first she extends her arms out to both sides as she spins. Later, she brings her arms in close to her body. Which statement below is correct?
The moment of inertia is larger when her arms are further from her axis of rotation.
The engine in a small airplane is specified to have a torque of 60 N•m. This engine drives a 2.0 m long, 40 kg propeller. How can you model this in terms of moments of inertia?
The propeller can be modeled as a rod that rotates about its center.
A student measures the mass of a solution before and after a chemical reaction takes place. In both cases the students measures the mass to be 50.25 g on an electronic balance with an uncertainty of 0.05 g. The student realizes that the ranges of uncertainty for each measurement overlap exactly. Which claim can the student make?
We can't know for sure whether or not the mass changed, but it seems reasonable to claim that the mass did not change, given that the ranges of uncertainty overlap.
This lab course is being offered as:
synchronous and online
This lab class will use which one of the following:
zoom
Generate a list of factors that might impact the energy output of a wind turbine. Number them and include at list 5 factors.
1. the speed of the wind 2. the height of the wind turbine 3. the pressure on the blades 4. the size of the blades 5. air density
A large cylindrical spool of light string is attached to a wall. The radius is 0.3 m and the spool has a mass of 25 kg. A child pulls on the string with a force of 55 N and the spool begins to rotate. Determine its angular acceleration.
14.7 rad/s2
The lab course will use groups of what size?
3-4 students
In earlier pre-lab notes, the differences between causal relationships and correlations were explored. In terms of the lab topic this week, the moment of inertia I, choose the best statement below for a single object of mass M.
A causal relationship exists between the distribution of mass of an object and its moment of inertia (I).
Students in a physics lab applied several mathematical models to determine where a ball projected horizontally off a table will land. Their resulting equation for determining where the ball will land (R) is given in the box below. Note that in the equation the term vx represents the horizontal velocity of the ball as it leaves the table, h is the height of the table, and g is the acceleration due to gravity. What type of relationship between height of table (h) and range (R) is represented in this equation? Choose the best statement below.
A causal relationship exists between the range (R) and height of table (h) if the horizontal velocity (vx) and acceleration due to gravity is held constant.
Much has been reported in the media about the relationship between SAT scores and a test-taker's family income. Consider the graph below concerning SAT Math Scores and family income as reported in The New York Times on August 27, 2009. What type of relationship between SAT test score and family income is demonstrated here?
A positive correlation exists between SAT test score and family income.
A scientist is trying to increase the number of cells grown in the lab. After giving 3 different treatments, she obtained the results presented in the table below. What one of the following represents possible dependent and independent variables for the investigation in this scenario?
DV = percent survival of cell cultures; IV = treatment
Over a period of 10 days a student measures the average growth of three similar plants grown in three different lighting conditions: A, B, C. What are possible dependent and independent variables for the investigation in this scenario?
DV = plant growth; IV = lighting conditions
A group of students conducted an experiment to determine what impacts the rate mold grows on bread. They decided to test whether or not preservatives in the bread made a difference in addition to the temperature in which the bread was stored. They purchased 2 loaves of bread that contain preservatives and 2 loaves that did not. They placed 5 pieces of each type of bread in 6 different environments of various temperatures ranging from 40°F to 85°F. The students were careful that each environment was basically identical except for temperature. After collecting data over 3 weeks the students made the claim that bread containing preservatives has a slower rate of mold growth when compared to bread without preservatives. They also made the claim that storing bread at lower temperatures reduces the rate of mold growth. Consider the following statements made by each student as they discuss what assumptions need to be discussed in their lab reports:Sam: In our report we need to write that we assumed that the two loaves of preservative-free bread were from the same batch and therefore identical to one another in terms of ingredients and age. We also need to write that we assumed the two loaves of bread with preservatives were identical in terms of ingredients and age. Alex: I agree with Sam but we should take it one step further and include a statement that we assumed that all four loaves of bread were actually of the same age and freshness as well. Troy: I agree with both of you, but we also need to include a statement that we assumed that we accurately measured the area of mold growth on each piece of bread.
I agree most with Alex's statement.
A student measures the temperature of a solution before and after a chemical reaction takes place. In both cases the student finds the temperature to be 25.2 °C, using the same thermometer with an uncertainty of 0.1 °C. Which claim made by the student below is correct?
I can't say for sure if the temperature changed or not because there is a range of uncertainty with each measurement. Because the ranges of uncertainty overlap, however, it is reasonable to make the claim that the temperature did not change.
Identify the independent (IV) and dependent (DV) variables for the reported study.
IV = number of hours sitting watching tv; DV = life span
Based on the plot shown, choose the mathematical model that best describes the relationship between the temperature of a steel beam and its length. Note that the origin shown on the graph is not (0,0). Assume that T is the temperature of the steel, L is the length of the beam, and α and β are constants that will be determined another way (i.e. fitting the data).
L = αT + β
When presenting assumptions in lab reports for this course, which of the following is the best course of action that should be taken?
List the assumptions, state exactly how they may have affected the results, and suggest what could be done, if anything, to improve the experiment in light of the assumptions.
One hundred samples of several different plant parts were placed in each of six sealed containers of equal volume. The amount of CO2 present in the containers at the beginning was 250 mL. After 2 days, it was at the level shown in the table. Suppose the researcher hypothesizes that the amount of CO2 absorption is related to the type of plant. If she selects container 5 as one of her containers, what conditions should she choose for a new container 6 to test her hypothesis?
Myrtle leaf, orange light, 27°C
A fitness store conducted a study and randomly chose 10 people to complete a survey regarding the number of months they owned a treadmill and the number of hours they spent exercising in the past week. The data is presented below. Note that it has been ordered from fewest to most months owned to make it easier to view the data. The relationship between the "number of months the treadmill was owned" and the "number of hours it was used by the buyer in the past week" is an example of:
Negative correlation
The hypothesis for the study actually presented in the New York Times article is
Number of hours sitting watching television impacts life span.
Below is a plot that represents the relationship between the radius of a cylinder and its volume for a constant cylinder height of 10 cm. Which type of curve most likely fits the data? Use the summary table of common graphs provided at the end of pre-lab 03 for additional guidance, if needed.
Power relationship (y = Cx^p, p>1
A group of students are provided with three objects all of the same mass and radius. The objects include a solid cylinder, a thin hoop (or cylindrical shell), and a solid sphere. The students are asked to predict which will get to the bottom of a ramp first if all three are released together from the same distance up the ramp. Which prediction is correct if the objects are listed in order from fastest to slowest?
Sphere (fastest), cylinder, hoop (slowest).
Two students want to determine if the mass of water changes during heating. Both start with about 40 g of water and heat their water samples the same way for the same length of time. After heating they each measure the mass of their own samples again using the same electronic balance as before (note that each student uses an electronic balance with a different uncertainty). Consider the data gathered by each student in the table below. Which set of conclusions made by the two students are correct, based on this data?
Student 1: The mass of the water changed during heating.Student 2: Considering my experimental range of uncertainty, the mass of the water did not change during heating.
The graph represents the amount of product created in a reaction aided by one of two enzymes. [Enzyme A is represented by the line mostly on top and Enzyme B is represented by the line with the sharper peak.]What is a possible hypothesis for the investigation portrayed in this scenario?
The amount of product created is related to the temperature of the reaction.
Two students collect data from grocery stores located in twelve different cities for the price per pound of apples, plums, and oranges. They compute the average price for each as well as the standard deviation for the data set they collected. What conclusion may be drawn about the price of apples, plums, and oranges using the graph below and employing the equivalency criterion?
The cost of oranges and the cost of apples are similar in some grocery stores due to the overlapping error bars shown, but plums cost less per pound.
Using the data collected by two groups shown in the figure below, what is the best statement that you can make about the value of the object's true mass?
The true value cannot be known.
Consider the following scenario: According to Sustainable Enterprises, coffee grounds can greatly benefit plants. They allow for a slow release of nitrogen and they can also increase nitrogen balance. Nitrogen helps plants use carbohydrates to gain energy. Nitrogen controls how plants take their form and how they function inside, and nitrogen helps plants make proteins that help them grow strong and healthy. Coffee grounds have been shown to increase the growth of plants because they have been said to release important nutrients used by the plants. According to Grow Joe, coffee grounds also release magnesium and zinc, micronutrients and amino acids. Without enough magnesium, plants may have brown/yellow older leaves. The coffee grounds can also feed earthworms; they loosen the soil; they retain water; and they release caffeine which repels slugs. Based on this information, students hypothesized that adding coffee grounds to the soil would affect the growth of Brassica rapa plants as measured by their leaf mass (size of leaves grown). They tested this by adding different amounts of coffee grounds to pots of soil before transplanting Brassica rapaseedlings into the pots. These amounts included 0, ¼, ½, ¾, and 1 cup of coffee grounds in each pot. Consider the following assumption made by the students:"The Brassica rapa seedlings transplanted into each pot were similar in health."
This is an appropriate assumption because the health of the seedling might impact leaf growth.
Below is a plot of the time it takes to travel 100 miles for cars moving at different speeds. The graph has already been fitted with a power law curve with the form y = 100 x-1. Using new variable names of t for time and s for speed, which of the mathematical models below best fits this scenario?
t = (100 miles) / s