1) A conservative system consists of a frictionless crane lifting a load of bricks at a construction site. The amount of work done by the crane against gravity is

a. less than the energy stored in the system

b. is equal to the energy stored in the bricks

c. equal to the kinetic energy of the system

d. greater than the energy stored in the bricks

2) A planet travels in an elliptical orbit. Which of these describes the relation of the planet's speed and energy?

a. The planet has a constant speed because its energy is constant.

b. The planet travels at a speed relative to its magnetic energy.

c. The planet goes slower when it is nearest the sun because it has less energy when it is closer to the sun.

d. When the planet is closest to the sun it goes fastest. Its kinetic energy is highest because potential energy is lowest. It goes slowest when it is farthest from the sun.

3) Calculate the work done by gravity on a 10 kg mass as it falls a distance of 3 meters. (Assume g=9.8m/s2g=9.8m/s2)

a. 30 J

b. 33 J

c. 0 J

d. 294 J

4) In what way does the period of a simple pendulum depend on its length?

a. The period of a simple pendulum does not depend on length.

b. Doubling the length of a simple pendulum causes the period to double.

c. Doubling the length of a simple pendulum causes the period to increase by a factor of 22.

d. Doubling the length of a simple pendulum causes the period to increase by a factor of square root of 2.

5) Suppose you build a Rube Goldberg machine in which one of the steps relies on a sharp object swinging down to cut a string. When you try the machine the first time, the string fails to break during this step. Which of the following strategies is NOT likely to resolve the issue?

a. Using a sharper cutting device.

b. Using a weaker string that cuts more easily.

c. Transferring more kinetic energy to the cutting device.

d. Running the machine a second time.

6) What role do energy transfers and transformations play in Rube Goldberg machines?

a. The machines work via chain reactions in which energy is transferred, but not transformed, in a series of multiple steps.

b. The machines work via chain reactions in which energy is transferred or transformed many times in a series of multiple steps.

c. The machines are designed to minimize the number of energy transfers and transformations in order to optimize efficiency.

d. The machines use energy transfers to accumulate power in a series of multiple steps.

7) As part of an investigation, students are required to build a device that transforms thermal energy to potential energy with an energy efficiency no less than 80%. One group of students builds a remote-controlled car that is able to push a ball along the path of a maze. Tests show that for each 5.0 J of work input, the work output is about 3.8 J.

Which statement correctly describes whether the car meets the device requirements?

a. No. Even though it does meet the efficiency requirement, it does not transform thermal energy to potential energy.

b. Yes. It meets the efficiency requirement, and it transforms thermal energy to potential energy.

c. No. Even though it does transform thermal energy to potential energy, it does not meet the efficiency requirement.

d. No. It does not meet the efficiency requirement, and it does not transform thermal energy to potential energy.

8) A force of 135 N is applied downward on a piston of radius 56.3 cm in a hydraulic system. If the other piston has a radius of 28.4 cm, what is the force applied to the other piston by the fluid?(1 point)

a. 0.254 N

b. 1,934 N

c. 34.4 N

d. 68.1 N