ACT science practice test 37

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.


A rollercoaster car is often used as a model of energy transformations. Resting at its starting point, the car has gravitational potential energy. As it moves along the track, the potential energy is converted to kinetic energy and then back to potential energy as the car approaches the rollercoaster's ending point.

An object's gravitational potential energy can be calculated as the product of the object's mass, acceleration due to gravity, and the object's height above the ground (PEg = m × g × h). In a frictionless system, the amount of potential energy at the beginning and end of the rollercoaster would be equal. However, friction between the car and the track causes frictional dissipation to transform some of the energy to heat and sound. The amount of energy dissipated due to friction can be calculated as the product of the frictional force on an object and the distance traveled by the object (Ffd).

A group of students built a marble rollercoaster out of foam pipe insulation tubing and tried to determine the conditions that would maximize the height of the rollercoaster's hill. The students conducted two experiments to study the effects of gravitational potential energy and frictional dissipation on the marble.

Experiment 1

Figure 5.1 shows the initial setup for the marble rollercoaster. A indicates the starting height (drop height) and C indicates the ending height (hill height) of the marble. B is the lowest point located halfway between A and C.

Figure 5.1

Students started with a drop height of 0.6 m and stretched the rollercoaster tubing out to a horizontal length of 1 m. They then varied the hill height until the marble was able to successfully reach the top of the hill without going over. To study the effects of the marble's initial gravitational potential energy, students conducted three more trials using different drop heights. Table 5.3 shows the results for each trial.

TABLE 5.3 Experiment 1

Experiment 2

Students started with a drop height of 1.2 m and stretched the rollercoaster tubing out to a horizontal length of 1.0 m. Students then varied the hill height until the marble was able to reach the top of the hill successfully without going over. To study the effects of frictional dissipation, students conducted two more trials using different horizontal track lengths. Table 5.4 shows the results for each trial.

TABLE 5.4 Experiment 2

1. When determining the gravitational potential energy of various objects on Earth, which variable would be considered a constant?

A. h
B. m
C. PEg
D. g

2. According to the formula provided in the passage, doubling the height of an object should:

A. double that object's potential energy.
B. half that object's mass.
C. double that object's mass.
D. halve that object's potential energy.

3. In a frictionless environment, with a drop height of A1 the marble should be able to reach a hill height (C in Figure 5.1) of:

A. 1.0 m.
B. 0.6 m.
C. 1.2 m.
D. 0.5 m.

4. In Experiment 1, students altered the drop height of the marble to test the effect of which of the following variables on hill height?

A. Frictional dissipation
B. Horizontal distance traveled
C. Initial gravitational potential energy
D. Mass of the marble

5. What was the maximum drop height used in either experiment?

A. 0.6 m
B. 1.2 m
C. 1.15 m
D. 1.5 m

6. Which of the following graphs best represents the relationship between drop height and hill height in Experiment 1?

A.
Figure 5.2
B.
Figure 5.3
C.
Figure 5.4
D.
Figure 5.5

7. The data in Table 5.4 indicate that lengthening the rollercoaster's track:

A. causes the effects of frictional dissipation to increase.
B. causes the effects of frictional dissipation to decrease, then increase.
C. has no effect on the amount of frictional dissipation.
D. causes the effects of frictional dissipation to decrease.

8. What was the smallest hill height recorded by the students in Experiment 2?

A. 0.5 m
B. 1.2 m
C. 1.06 m
D. 0.97 m

9. The students used drop height as the dependent variable in:

A. Experiment 1 only.
B. Experiment 2 only.
C. both Experiments 1 and 2.
D. neither Experiment 1 nor 2.

10. If the students were to carry out a third experiment to study the relationship between marble mass and hill height, how would the data table for this new experiment compare to Table 5.3?

A. They would need to add an extra column between drop height and hill height for marble mass.
B. They would need to replace the hill height column with a column for marble mass.
C. They would need to add extra rows to the bottom of the table for additional trials.
D. They would need to replace the horizontal distance column with a column for marble mass.

11. Based on the data for the two experiments, at which point in Figure 5.1 does the marble have the greatest gravitational potential energy?

A. Point A
B. Between points A and B
C. Point C
D. Point B

12. Which of the following is a similarity between Experiments 1 and 2?

A. Both experiments began with an initial drop height of 0.6 m.
B. The effect of the independent variable was studied by measuring hill height.
C. Horizontal distance traveled was held constant in both experiments.
D. The initial gravitational potential energy increased with each trial.

13. Which of the following energy transformations is not demonstrated by the marble rollercoaster in either Experiment 1 or Experiment 2?

A. Mechanical energy to thermal energy
B. Mechanical energy to sound
C. Mechanical energy to chemical energy
D. Potential energy to kinetic energy

14. In Experiment 2, a fourth trial using a horizontal distance of 1.75 m would most likely result in a hill height:

A. greater than the hill height recorded in Trial 2.
B. less than the hill height recorded in Trial 3.
C. close to the hill height recorded in Trial 1.
D. between the hill heights recorded in Trials 2 and 3.