Inv7.Exp1 - Concepts Quiz

A student (S) carries a bag 3 meters across a level room. The free-body diagram on the bag is shown. The Fs label represents the force from the student. The force of gravity and the upwards force from the student do_______________.

A student (S) carries a bag 3 meters across a level room. The free-body diagram on the bag is shown. The Fs label represents the force from the student. The force of gravity and the upwards force from the student do zero work. Since both forces are ______________________, neither force does work.

A student (S) carries a bag 3 meters across a level room. The free-body diagram on the bag is shown. The Fs label represents the force from the student. Friction force does _______________ on the box since its force is in the same direction as the motion.

A student is pulling their dog in a wagon. The velocity of the dog and wagon system is shown in the table. Which of the following are true about the energy of the dog-wagon system? Select all that apply.

• Positive work is being done on the system.
• Negative work is being done on the system
• The kinetic energy of the system is constant.
• The kinetic energy of the system is decreasing.
• The kinetic energy of the system is increasing.

Two students are sitting in a canoe on a still lake. Using identical paddles, both students row on opposite sides of the canoe. The style of rowing the canoe is shown in the image. The students row simultaneously together, causing the canoe to move forwards. To row, the student’s reach out in position A and pull the paddle back in position B. How does reaching out and pulling the paddle a farther distance impact the canoe?

• As the students pull a farther distance, there is a greater displacement, so the work done by the students decreases.
• As the students pull a farther distance, there is a greater displacement, so the work done by the students increases.
• As the students pull a farther distance, there is a lesser displacement, so the kinetic energy of the boat increases.
• As the students pull a farther distance, there is a lesser displacement, so the power of the students’ rowing increases.

A large semi-truck uses a pneumatic braking system. Image A shows a portion of the system that functions in the front end. The pneumatic system uses compressible fluid to multiply forces. When the foot brake is applied, compressed air is pushed through the pipes, as shown in the image. The air hits the diaphragm in the brake chamber, which functions as a piston. As the compressed air pushes the piston down, the S-cam rotates, activating the foundation brakes. As the air pressure increases in the pipes, the foundation brakes on each wheel are engaged. A driver exerts a force on the foot brakes, causing the air pressure to change. The foundation brakes are applied and friction slows down the truck. How does decreasing the amount of time to compress the brakes impact the power?

• Decreasing the time to compress the brakes increases the power since the change in kinetic energy increases.
• Decreasing the time to compress the brakes decreases the power since the change in kinetic energy decreases.
• Decreasing the time to compress the brakes decreases the power since the change in kinetic energy occurs quicker.
• Decreasing the time to compress the brakes increases the power since the change in kinetic energy occurs quicker.

The air compressor in the truck allows the pressure in the tubes to remain controlled. If the pressure remains constant, how does increasing the area of the diaphragm, or piston, on the foundation brakes impact the force required to stop the truck? Explain your answer and reference kinetic energy. If the pressure remains constant, the force and area on the piston are _________________.

The air compressor in the truck allows the pressure in the tubes to remain controlled. If the pressure remains constant, how does increasing the area of the diaphragm, or piston, on the foundation brakes impact the force required to stop the truck? Explain your answer and reference kinetic energy. Increasing the area of the piston _________________ the air pressure applies on the brakes.

The air compressor in the truck allows the pressure in the tubes to remain controlled. If the pressure remains constant, how does increasing the area of the diaphragm, or piston, on the foundation brakes impact the force required to stop the truck? Explain your answer and reference kinetic energy. Since the pressure on the brakes increases, the truck will slow down quicker. As the truck slows down, its ___________________________.

Four cars of different masses are driven down a highway at different velocities. The masses and velocities of each car are expressed in terms of m and v, as shown in the table. Before approaching a traffic light, the brakes of all four cars are applied with the same force. Which cars will need to start having their brakes applied the farthest distance from the traffic light in order to stop at the red light?

• Car 1 and car 3 will need to have their brakes applied the farthest away since they have the least kinetic energy.
• Car 2 and car 4 will need to have their brakes applied the farthest away since they have the least kinetic energy.
• Car 1 and car 4 will need to have their brakes applied the farthest away since they require the most work done to stop the cars.
• Car 2 and car 4 will need to have their brakes applied the farthest away since they require the most work done to stop the cars.