ACT Science Practice Test 89

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.

Engineers studied the trajectories of a cannonball launched from a cannon under various conditions.

Study 1

On a level surface during a mild day, engineers launched a cannonball from a cannon as shown in Figure 1.

Figure 1

A camera was fixed atop the cannon so that it would point in the direction of the cannonball's launch. A receiver was also fixed to the cannon to record the cannonball's position as recorded by the camera.

As the cannonball traveled through the air, angle θ, which is defined in Figure 1, consistently changed. The change in θ was captured by the camera every 0.25 seconds after launch until the cannonball landed. For each recorded image, θ was measured (Figure 2).

Figure 2

Furthermore, every 0.25 sec after launch, the receiver sent out a radar pulse, part of which was reflected by the cannonball to the receiver. The roundtrip travel time of each pulse was recorded to determine the distance, d, between the receiver and the ball at any given time (see Figure 3).

Figure 3

Using d and θ, the engineers determined the ball's height, h, and distance, r, at the end of each 0.25 sec interval. A curve plotting h versus r was constructed.

This procedure was followed using cannonball launch starting speeds of 135 ft/sec, 150 ft/sec, and 180 ft/sec. For each launch speed, the ball was launched at θ = 30°. The curves representing h and r for each of the launch speeds were connected by lines for time, t = 2 sec, 3 sec, 4 sec, and 5 sec after launch (see Figure 4).

Figure 4

Study 2

Using an algorithm, the engineers calculated h and r at 0.25 sec intervals for the same cannonball launched in a vacuum in otherwise similar conditions to those in Study 1. The results are plotted in Figure 5.

Figure 5

1. Suppose the cannonball were launched at 30° in a vacuum from a height of 5 ft. Based on Figure 5, the cannonball would land approximately how many feet farther from the cannon if it were launched at 150 ft/sec than if it were launched at 135 ft/sec?

A. 50 ft
B. 150 ft
C. 500 ft
D. 650 ft

2. While the cannonball was in flight, how often did the camera record the position of the ball?

F. Once per second
G. Twice per second
H. Three times per second
J. Four times per second

3. The cannon was an instrumental weapon used during the Ottoman invasion of the city of Constantinople in 1453. Assume that cannonballs identical to those used in Study 1 were launched on a windless day with a starting height of 5 ft above the ground and an angle of θ = 30°. If the launch speed of each cannonball were 180 ft/sec, how close would the cannon have needed to be to the 40-ft-tall wall surrounding Constantinople in order to travel over it?

A. 425 ft
B. 575 ft
C. 700 ft
D. 850 ft

4. Based on Figure 4, as the initial speed of the launched cannonball was increased, how did the values of h and r change at t = 4 sec?

h r

F. decreased decreased
G. decreased increased
H. increased decreased
J. increased increased

5. Based on Figure 5, if the ball were launched in a vacuum from a height of 5 ft at 135 ft/sec and θ = 30°, how long would the cannonball most likely be in flight from launch to landing?

A. Between 4 sec and 5 sec
B. Between 5 sec and 6 sec
C. Between 6 sec and 7 sec
D. Between 7 sec and 8 sec

6. Based on Figure 3, if c represents the speed of light, which of the following represents the time taken by each radar pulse to make the roundtrip between the receiver and the ball?

F. 2c/d
G. 2d/c
H. c/r
J. r/c

The apoptotic index (AI) for a group of dividing cells is calculated as follows:

Figure 1 shows the AI for a culture of fibroblast cells as a function of the surrounding concentration in parts per million (ppm) of a cell toxin.

Figure 1

One thousand actively dividing fibroblast cells in culture were studied. Figure 2 shows the distribution of the cells in each of the stages of the dividing cell cycle.

Figure 2

Electron micrographs were taken of the fibroblasts in culture. Figure 3 shows an example of cells in each of the 4 stages of the dividing cell cycle. Although the cells are not arranged in the sequence of the cell cycle, each stage is shown only once.

Figure 3

7. Which cell in Figure 3 is most likely in the stage of the cell cycle during which cytokinesis is occurring as mitosis nears completion?

A. Cell 1
B. Cell 2
C. Cell 3
D. Cell 4

8. Based on Figure 1, of the fibroblast cells that are surrounded by a toxin concentration of 90 ppm, the percent that are in apoptosis most likely is represented by which of the following ranges?

F. Less than 0.5%
G. Between 0.5% and 0.6%
H. Between 0.6% and 0.7%
J. Greater than 0.7%

9. Which of the following cells in Figure 3 is most likely in the first stage of the actively dividing cell cycle?

A. Cell 1
B. Cell 2
C. Cell 3
D. Cell 4

10. According to Figure 2, how did the number of fibroblast cells in stage G2 compare with the number of cells in stage S? The number in G2 was approximately:

F. 2 times as great as the number in S.
G. 3 times as great as the number in S.
H. as great as the number in S.
J. as great as the number in S.

11. Based on Figure 2, of the fibroblast cells that were in the actively dividing cell cycle, the proportion that were in G1 is closest to which of the following?