21. The graph shows the velocity of an object over time. Six points on the graph are labeled P, Q, R, S, T, and U. 

 

 

At which two points is the net force acting on the object zero?

 

Measuring which of the following variables would most help the scientists determine the relationship between air density and net force on the ball as it falls toward Earth?

Part A. Energy is needed to move the particles closer together in

Part A. During the experiment, as the light passed through the double slits it was

Two adults push a couch across a floor. Each adult applies a 200 N force to the couch in the same direction. There is a frictional force of 300 N acting on the moving couch.

 

Which of the following diagrams best represents the applied and frictional forces on the moving couch?

Two positively charged particles, each with a charge of +q, are placed near each other, as shown in the diagram.

 

Part A. Which of the following best represents the direction of the electrostatic force acting on each particle?

The graph shows how a runner’s position changes over three time intervals, X, Y, and Z.

 

Based on the runner’s speed during each time interval, which of the following orders the intervals from slowest speed to fastest speed?

 

Which of the following describes the voltage drop across the 4 Ω resistor?

Airplanes can land on large ships called aircraft carriers. After an airplane lands on an aircraft carrier, a strong cable causes the airplane to slow down and stop. The diagrams show an airplane and the cable before and just after the plane lands on an aircraft carrier.

 

Which of the following describes a change that would reduce the force on the plane during landing?

The following section focuses on investigating circuits.

The students built a circuit with a battery, a switch, and a motor. The circuit is shown. When the switch was closed, the motor began to spin.

 

Which of the following best describes what caused the motor to spin?

This question has three parts. Be sure to label each part of your response.

 

The students built a circuit that includes a buzzer, as shown. When the amount of current passing through the buzzer increases, the volume of the buzzer’s sound also increases.

 

 

Part A. The students want to increase the volume of the sound coming from the buzzer. Identify whether the students should increase or decrease the resistance in the variable resistor to increase the volume of the buzzer’s sound. Explain your reasoning.

Part B. When the students close the switch and set the variable resistor to 1950 Ω, the buzzer produces a sound with a constant frequency of 2900 Hz. Sound waves travel through air at a speed of 343 m/s.

 

Calculate the wavelength of the sound wave produced by the buzzer when the variable resistor is set to 1950 Ω. Show your calculations and include units in your answer.

Part C. The students place the circuit in a waterproof container and then put the container under water while the buzzer is making sound. The frequency of the buzzer’s sound wave does not change as it moves from the air in the container into the water.

 

Compare the wavelength of the sound wave in air with the wavelength of the sound wave in water. Explain your reasoning

In Diagram 1, objects X and Y are separated by distance d, as shown. Object Y’s mass is twice the amount of object X’s mass.

 

In Diagram 2, object Y is replaced with object Z, as shown. Object Z’s mass is the same as object X’s mass.

 

Engineers are testing the efficiency of four types of solar panels. The engineers plan to use each solar panel as the energy source in an electric circuit. They will measure the energy output from each solar panel.

 

To compare the efficiency of the solar panels, which of the following should the engineers keep constant?

 

Select two statements that best describe the block at the moment in time shown in the diagram.

This question has four parts.

 

A spring is compressed between a 10 kg block and a 5 kg block that are at rest on a frictionless surface. Then the spring is released. The diagrams show the two-block system before and after the spring is released.

 

 

Part A. Determine the momentum of the system before and after the spring is released. Explain your reasoning using the law of conservation of momentum.

Part D. Energy is also conserved in this system.

 

Describe how energy is conserved when the spring is released. Be sure to discuss both potential and kinetic energy.