Question

12 scientists today are studying tidal power as an alternative energy source for generating electricity. some scientists conclude that tidal power is a good alternative source of energy because it uses a natural process, does not rely on fossil fuels, and does not release greenhouse gases. these scientists recommend building tidal power plants around the united states in locations with high tidal power potential. other scientist conclude that tidal power is not a good alternative energy source because tidal power plants can negatively impact the surrounding ecosystem by killing marine animals, restricting fish migration, reducing the natural flow of water, and causing silt build up in waterways. these scientists recommend not building tidal power plants in u.s. waterways. both conclusion are based on valid data and scientific reasoning. how can both conclusions be valid? 4 marks a. the two groups of scientists believe different theories about the process of generating electricity. b. the two groups of scientists are looking at different specific aspects of the same scientific problem. c. the two groups of scientists collect and analyze data about all types of possible alternative energy sources. d. the two groups of scientists are on the opposite sides of the debate on whether the united states needs to find clean alternative energy sources. 13 one way to determine the age of earth is to measure the ratio of certain radioactive elements to their more stable forms. by comparing the amount of the radioactive form of an object with the stable one, and by knowing how long it takes to turn from one to the other, scientists can estimate the age of the object. some people argue that the decay rate has not always been the same and that it can be much faster than scientists have measured in labs. nuclear power plants use radioactive elements to produce power because, during the decay process, energy is released. if scientists are wrong about earth’s age based on radioactive material and the decay rates are really much faster, how would nuclear power plants be affected? 3 marks a. nuclear fuel would remain useful longer. b. the rate of energy release would be higher. c. the amount of energy released would be less. d. nuclear fuel would generate less radioactivity. page 6 of 9 14 moving objects, such as automobiles, have kinetic energy (ke), which is measured in joules. this energy can be calculated using the following formula: ke = ½ mv² a person drives an automobile with a mass of 450 kilograms at a velocity of 26 meters per second. the driver accelerates to a velocity of 30 meters per second. the difference in the auto - mobiles’s kinetic energy between the two velocities is ……………… joules. you may use the calculator. 3 marks a. 152100 joules b. 202500 joules c. 50400 joules d. none of these above

Explanation:

Question 12

To determine why both conclusions about tidal power are valid, we analyze each option:

• Option A: The debate isn't about electricity generation theories but tidal power's pros/cons. Eliminate A.
• Option B: One group focuses on environmental benefits (no fossil fuels, no greenhouse gases), the other on ecosystem harm (killing marine life, silt buildup). They examine different aspects of tidal power, so both conclusions can be valid. This fits.
• Option C: The scientists are studying tidal power, not all alternative energy sources. Eliminate C.
• Option D: Both groups likely agree on the need for clean energy; their debate is about tidal power's suitability. Eliminate D.

If decay rates are faster than measured, we analyze the impact on nuclear power plants:

• Option A: Faster decay means fuel is used up faster, so it won't last longer. Eliminate A.
• Option B: Faster decay releases energy more quickly, so the rate of energy release would be higher. This makes sense.
• Option C: Faster decay would release more energy, not less. Eliminate C.
• Option D: Faster decay would generate more radioactivity, not less. Eliminate D.

Step1: Recall the kinetic energy formula $KE = \frac{1}{2}mv^2$.

We need to find the difference between $KE$ at $v = 30$ m/s and $v = 26$ m/s, with $m = 450$ kg.

Step2: Calculate $KE$ at $v = 30$ m/s.

Substitute $m = 450$ and $v = 30$ into the formula:
$KE_1 = \frac{1}{2} \times 450 \times (30)^2 = 225 \times 900 = 202500$ joules.

Step3: Calculate $KE$ at $v = 26$ m/s.

Substitute $m = 450$ and $v = 26$ into the formula:
$KE_2 = \frac{1}{2} \times 450 \times (26)^2 = 225 \times 676 = 152100$ joules.

Step4: Find the difference.

Subtract $KE_2$ from $KE_1$: $202500 - 152100 = 50400$ joules. Wait, no—wait, the options have 50400 as option C? Wait, no, wait my calculation: Wait, $\frac{1}{2} \times 450 = 225$. $30^2 = 900$, so $225 \times 900 = 202500$. $26^2 = 676$, $225 \times 676 = 152100$. Then $202500 - 152100 = 50400$? Wait, but option C is 50400. Wait, but let me check again. Wait, the formula is $KE = 0.5mv^2$. So for $v=30$: $0.5*450*900 = 225*900 = 202500$. For $v=26$: $0.5*450*676 = 225*676 = 152100$. Difference: $202500 - 152100 = 50400$. So option C is 50400. Wait, but wait, the options: A is 152100, B is 202500, C is 50400. So the difference is 50400, which is option C? Wait, but let me check again. Wait, 4500.5=225. 30 squared is 900, 225900=202500. 26 squared is 676, 225*676=152100. 202500-152100=50400. So the answer is C? Wait, but the options: C is 50400. So the difference is 50400, which is option C.

Answer:

B. The two groups of scientists are looking at different specific aspects of the same scientific problem.

Question 13