ACT Science Practice Test 100

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.


Friction is the resistance to the movement of one object past another object with which the first object is in contact. A group of students performed several experiments using rectangular blocks of various materials and a smooth inclined plane 2 meters in length. To compare how different materials are affected by friction, the blocks were placed at the top of the plane and released to travel the 2-meter distance. The time in seconds (s) that it took for each block to reach the end of the inclined plane was recorded.

Experiment 1

The group of students wanted to know which materials moved down the plane in the shortest amount of time. The students used blocks of wood, steel, aluminum, glass, plastic, and concrete. The dimensions of each block were the same, the volume of each block remained constant, and the mass of the blocks was varied. The incline of the plane was set at 45° for each trial. The students conducted 3 trials for each material, and recorded the results in Table 1.

Experiment 2

The students conducted a similar experiment as in Experiment 1 to test the effect of volume on the time that it took for the blocks to move down the inclined plane. The results are shown in Table 2.

Experiment 3

Objects can be rated according to their ability to move efficiently. The students created a scale from 5 to 30 (least to most resistant to motion due to friction) and tested four objects of a known rating. Three trials were conducted for each object, using the same methods as in Experiment 1. The results are shown in Table 3.

1. If Experiment 1 were repeated with a plane length of 4 meters, the movement time for the wood block, in seconds, would be closest to:

A. 3.28
B. 1.64
C. 1.32
D. 0.82

2. What value would the plastic object used in Experiment 2 likely have on the scale described in Experiment 3?

F. Less than 5
G. Between 5 and 9
H. Between 9 and 13
J. Between 13 and 19

3. A furniture maker wants to build a chair whose legs can move more easily across a smooth wooden floor. Based on Experiment 3, which of the following object ratings should the chair material have to best accomplish that goal?

A. 5
B. 9
C. 13
D. 19

4. In which of the following ways are the designs of Experiments 1 and 2 different?

F. In Experiment 1 mass was held constant, while in Experiment 2 it varied.
G. In Experiment 1 volume varied, while in Experiment 2 it was held constant.
H. In Experiment 1 volume was held constant, while in Experiment 2 mass was varied.
J. In Experiment 1 volume was held constant, while in Experiment 2 mass was held constant.

5. Based on the assumption that the loss in speed that is due to friction is responsible for longer travel times down the inclined plane, which of the following lists of objects used in Experiment 2 is in order of increasing loss of speed due to friction?

A. Plastic, aluminum, wood, concrete
B. Glass, aluminum, wood, concrete
C. Aluminum, steel, wood, concrete
D. Concrete, wood, glass, aluminum

6. Based on the results of Experiments 1 and 2, as the volume of the blocks increased, the average time it took each block to move down the inclined plane:

F. increased only.
G. decreased only.
H. increased for some blocks and decreased for other blocks.
J. remained the same.