Sound waves travel through a medium by mechanically disturbing the particles of that medium. As particles in the medium are displaced by the sound wave, they in turn act upon neighboring particles. In this fashion, the wave travels through the medium through a parallel series of disturbed particles. Like in other forms of motion, the rate at which the sound wave travels can be measured by dividing the distance over which the wave travels by the time required for it to do so.

Study 1
A group of students hypothesizes that the velocity of sound is dependent upon the density of the medium through which it passes. They propose that with more matter in a given space, each particle needs to travel a shorter distance to disturb the adjacent particles. Using two microphones and a high speed recording device, the students measured the delay from the first microphone to the second. They chose a variety of media, shown in Table 1, and measured the velocity of sound through each using their two-microphone setup. The results are found in Table 1.

Study 2
The students wanted to test their hypothesis by using the same medium at different densities. To do this, they heated pure water to various temperatures and repeated the procedure described in Study 1. Their results can be found in Table 2.

According to Study 2, water at which of the following temperatures yields the greatest velocity of sound?

A researcher is investigating new solar technology. The researcher looks at combinations of solar panels and solar rechargeable batteries that were provided from research labs A, B, C and D. The combinations of solar panels and solar rechargeable batteries are measured for their efficiency, the amount of time it takes to fully charge a battery, and the life of each fully charged battery used to power a home. The experiments were conducted using a UV light. The batteries recharge when the solar panels are exposed to UV light and are depleted of charge when being used for power. The solar panels will not recharge the batteries on cloudy days.

Based on the provided data, what relationship can be found between the efficiency of the solar panel and the amount of time it takes to fully charge the battery? Assume that the production differences between batteries and solar panels is negligible across the different labs.

A physicist wishes to study the trajectory of a ball launched horizontally. She varies parameters such as the launching velocity, starting height, and mass of the ball. For each trajectory, she records the time of flight (in seconds) and horizontal displacement (in meters). She assumes air resistance is negligible.

Figure 1

Using all of the data she collects, she constructs the following table:

Table 1

If all of trial 3 were redone with a launching velocity of 20 m/s instead of 10 m/s, then compared to the data for trial 3 presented in the table, the horizontal displacement for all data points would be which of the following?

A student conducts an experiment in which she suspends a ball mass from a string and swings it in a perfect circular motion. What is often referred to as centrifugal force appears to push the ball away from the center of the circle of its motion with a force in the string. The force is described by the formula where is the mass, is the speed of the ball, and is the radius of its motion.

The student first tries the experiment spinning the ball at a speed of . The resulting force is . What would the force in the string be if she sped up the ball to a speed of ?

Experiment 1

A scientist develops the following setup, shown in Figure 1 below, to study the charges of radioactive particles. A radioactive sample is placed into a lead box that has an open column such that the particles can only exit from one direction. A detector is placed in front of the opening. A metric ruler measuring in centimeters (cm), is aligned on the detector such that zero is directly in front of the opening of the column, with positive values extending to the left and negative values extending to the right. On the left side of the experimental setup, there is a device that generates a magnetic field that attracts positively charged particles and repels negatively charged particles.

Figure 1.

The device detects particles in three different places: alpha, α; beta, β; and gamma, γ; as labeled in Figure 1. The paths these particles take from the source of radioactivity are shown.

Experiment 2

A different scientist finds the following data, shown in Table 1, about the energies of the α, β, and γ particles by observing what kinds of materials through which the particles can pass. This scientist assumes that the ability of particles to pass through thicker and denser barriers is indicative of higher energy. Table 1 summarizes whether or not each type of particle was detected when each of the following barriers is placed between the radioactivity source and the detector. The paper and aluminum foil are both 1 millimeters thick, and the concrete wall is 1 meter thick.

Based on the trajectories of the particles in Experiment 1, what can be concluded about the relative charges of the particles?

The graph below depicts the position of three different cars over a 15-second time interval.

At the point where all three cars meet, which car is traveling the fastest?

Mary is performing an experiment involving the electromagnetic spectrum. She observes several different types of waves and records their wavelength, frequency, and speed.

Which type of radiation has the greatest wavelength?

A physicist wishes to study the trajectory of a ball launched horizontally. She varies parameters such as the launching velocity, starting height, and mass of the ball. For each trajectory, she records the time of flight (in seconds) and horizontal displacement (in meters). She assumes air resistance is negligible.

Figure 1

Using all of the data she collects, she constructs the following table:

Table 1

In Trial 1, if a fourth data point were collected in which the ball was thrown with a launching velocity of 40 m/s, what would be the approximate horizontal displacement in meters?

A student was interested in determining the relationship between the current, voltage, and resistance in a direct circuit, such as those exemplified by batteries connected to light bulbs. The student built the circuit presented in Figure 1 using a 2 ohm resistor.

Figure 1:

The current that flows through the circuit can be calculated using the equation , where is the voltage of the battery, is the current flowing through the circuit, and is the resistance of the resistor.

The student used a 2 ohm resistor and batteries of various voltages to obtain the results in Table 1. The currents shown in the table are NOT calculated using the formula , but instead directly measured from the circuit using an ammeter. It is important to note that the measured current will only exactly equal the calculated current if the system contains no internal resistance.

In Experiment 1, how much current is most likely flowing through the circuit?

Engineers are evaluating four potential technologies. These technologies are to be used as power plants that are considered "clean" energy. The estimated energy output of these plants were calculated and the resources needed to run these were also listed.

What is the expected energy output, in kiloWatt hours per a day, if there were no resource limitations?