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Drilling mud (DM) is a suspension of clay particles in water. When a well is drilled, DM is injected into the hole to lubricate the drill. After this use, the DM is brought back up to the surface and then disposed of by spraying it on adjacent land areas.
A cover of DM on plants and soil can affect the albedo (proportion of the total incoming solar radiation that is reflected from a surface), which in turn can affect the soil temperature. The effect of a cover of DM on the albedo and the soil temperature of an unsloped, semiarid grassland area was studied from July 1 to August 9 of a particular year.
On June 30, 3 plots (Plots 1−3), each 10 m by 40 m, were established in the grassland area. For all the plots, the types of vegetation present were the same, as was the den- sity of the vegetation cover. At the center of each plot, a soil temperature sensor was buried in the soil at a depth of 2.5 cm. An instrument that measures incoming and reflected solar radiation was suspended 60 cm above the center of each plot.
An amount of DM equivalent to 40 cubic meters per hectare (m3/ha) was then sprayed evenly on Plot 2. (One hectare equals 10,000 m2.) An amount equivalent to 80 m3/ha was sprayed evenly on Plot 3. No DM was sprayed on Plot 1.
For each plot, the albedo was calculated for each cloudless day during the study period using measurements of incoming and reflected solar radiation taken at noon on those days (see Figure 1).
For each plot, the sensor recorded the soil temperature every 5 sec over the study period. From these data, the average soil temperature of each plot was determined for each day (see Figure 2).
1. Albedo was measured at noon because that time of day is when solar radiation reaching the ground is:
F. 100% reflected.
G. 100% absorbed.
H. least intense.
J. most intense.
2. Why was the study designed so that the 3 plots had the same types of vegetation present and the same density of vegetation cover? These conditions ensured that any variations in albedo and soil temperature would most likely be attributable only to variations among the plots in the:
A. amount of DM sprayed.
B. type of soil present.
C. plot area.
D. plot slope.
3. Based on Figure 1, on August 3, what percent of incoming solar radiation was NOT reflected from Plot 2 ?
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In 2 experiments, a student pulled each of 3 blocks in a straight line across a flat, horizontal surface.
In Experiment 1, the student measured the pulling force (the force required to move each block at a constant speed) and plotted the pulling force, in newtons (N), versus block mass, in kilograms (kg). The results are shown in Figure 1.
In Experiment 2, the student measured the speed versus time of a 2.00 kg block, a 2.50 kg block, and a 3.00 kg block as each block was pulled across the surface with a constant 30 N force. The results are shown in Figure 2.
1. If a block was pulled toward the east, the frictional force exerted on the block by the surface was directed toward the:
2. Based on Figure 2, what is the order of the 3 blocks, from the block that required the shortest time to reach 15 m/sec to the block that required the longest time to reach 15 m/sec ?
E. 2.00 kg block, 2.50 kg block, 3.00 kg block
F. 2.00 kg block, 3.00 kg block, 2.50 kg block
G. 3.00 kg block, 2.00 kg block, 2.50 kg block
H. 3.00 kg block, 2.50 kg block, 2.00 kg block
3. Based on Figure 2, what was the approximate value of the acceleration of the 3.00 kg block?
A. 0.0 m/sec2
B. 5.0 m/sec2
C. 15.0 m/sec2
D. 20.0 m/sec2
4. Based on Figure 1, the results of Experiment 1 are best modeled by which of the following equations?
E. Block speed (m/sec) = 0.2 × time (sec)
F. Block speed (m/sec) = 5.0 × time (sec)
G. Pulling force (N) = 0.2 × block mass (kg)
H. Pulling force (N) = 5.0 × block mass (kg)
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The relationship between speed, mass, weight, and friction was studied using a toy car that carried additional masses. The car was placed on a 1m inclined plane and released. The time it took to go down the incline and the time it took to go one meter beyond the incline were recorded.
Additional masses were added to the car as it was released down the incline plane. The car has a mass of 50 g. The plane was angled at a 25 degree angle.
The incline of the plane was changed to determine its effect on the time it took the car to travel down the plane. There were no additional masses placed on the car.
How is the design of Experiment 1 different from that of Experiment 2?
A. Experiment 2 varied the mass on the car while Experiment 1 varied the angle of the plane.
B. Experiment 1 varied the mass on the car while Experiment 2 varied the angle of the plane.
C. Experiment 1 and Experiment 2 tested the same variable in different ways.
D. Experiment 1 and Experiment 2 have no differences.