Nokea
What characterizes laminar flow?
- A. Smooth, parallel layers of fluid particles
- B. Erratic and turbulent motion of fluid particles
- C. High viscosity hindering flow
- D. Incompressibility of the fluid
Correct Answer: A
Rationale: Laminar flow is characterized by the smooth, parallel movement of fluid particles along layers in a predictable manner. This flow regime occurs at low velocities and is in contrast to turbulent flow, where fluid particles exhibit erratic and chaotic motion. The viscosity of the fluid does not hinder laminar flow; instead, it influences the resistance to flow. Incompressibility is a property of fluids but does not specifically define laminar flow. Therefore, the correct answer is A as it accurately describes the behavior of fluid particles in laminar flow, making B, C, and D incorrect.
You may also like to solve these questions
A bicycle and a car are both traveling at a rate of 5 m/s. Which statement is true?
- A. The bicycle has more kinetic energy than the car.
- B. The bicycle has less kinetic energy than the car.
- C. Both vehicles have the same amount of kinetic energy.
- D. Only the car has kinetic energy.
Correct Answer: B
Rationale: Kinetic energy is determined by both the mass and the velocity of an object. While both the bicycle and the car are moving at the same velocity (5 m/s), the car has significantly more mass than the bicycle. As a result, the car has more kinetic energy than the bicycle, even though their speeds are identical. Therefore, choice B is correct. Choices A, C, and D are incorrect because they do not consider the influence of mass on kinetic energy. Choice A is incorrect as the car has more kinetic energy due to its greater mass. Choice C is incorrect because the vehicles have different masses. Choice D is incorrect as both the bicycle and the car possess kinetic energy.
A circular running track has a circumference of 2,500 meters. What is the radius of the track?
- A. 1,000 m
- B. 400 m
- C. 25 m
- D. 12 m
Correct Answer: B
Rationale: The radius of a circular track can be calculated using the formula: Circumference = 2 π radius. Given that the circumference of the track is 2,500 m, we can plug this into the formula and solve for the radius: 2,500 = 2 π radius. Dividing both sides by 2π gives: radius = 2,500 / (2 3.1416) ≈ 397.89 m. Therefore, the closest answer is 400 m, making option B the correct choice. Option A (1,000 m) is too large, option C (25 m) is too small, and option D (12 m) is significantly smaller than the calculated radius.
When the heat of a reaction is negative, which statement is true?
- A. The products have less energy and are less stable.
- B. The products have more energy and are more stable.
- C. The products have less energy and are more stable.
- D. The products have more energy and are less stable.
Correct Answer: C
Rationale: When the heat of a reaction is negative, it indicates that the reaction releases energy in the form of heat. This means that the products have lower energy levels compared to the reactants. Lower energy levels are associated with greater stability in chemical systems. Therefore, when the heat of a reaction is negative, the products are more stable due to having less energy than the reactants. Choice A, stating that the products have less energy and are less stable, is incorrect as lower energy levels imply greater stability. Choice B, stating that the products have more energy and are more stable, is incorrect as lower energy levels lead to higher stability. Choice D, stating that the products have more energy and are less stable, is incorrect as lower energy levels are associated with higher stability.
As a vehicle positioned at the peak of a hill rolls downhill, its potential energy transforms into:
- A. Thermal energy
- B. Neither thermal nor kinetic energy
- C. A combination of thermal and kinetic energy
- D. Kinetic energy
Correct Answer: D
Rationale: The correct answer is D: Kinetic energy. Potential energy is converted into kinetic energy as the vehicle moves downhill. Kinetic energy is the energy possessed by a moving object. Thermal energy is not produced in this scenario because the energy transformation is mainly from potential to kinetic energy, not involving heat generation. Choices A, B, and C are incorrect because the primary energy transformation in this scenario is from potential to kinetic energy, not involving thermal energy.
A 50-kg box of iron fishing weights is balanced at the edge of a table. Peter gives it a push, and it falls 2 meters to the floor. Which of the following statements is true?
- A. Once the box hits the floor, it loses both its kinetic and potential energy.
- B. The box had kinetic energy only when it was balanced at the edge of the table.
- C. The box had both kinetic and potential energy after it fell.
- D. Once the box hits the floor, it loses all its kinetic energy.
Correct Answer: C
Rationale: When the box is balanced at the edge of the table, it has potential energy due to its position above the ground. As Peter gives it a push, and it falls 2 meters to the floor, the box then has both kinetic energy (due to its motion) and potential energy (due to gravity). Therefore, the correct statement is that the box had both kinetic and potential energy after it fell. Option A is incorrect because the box retains its energy forms even after hitting the floor. Option B is incorrect as the box has kinetic energy both before and after falling. Option D is incorrect as the box still possesses kinetic energy even after hitting the floor.