Nokea
Amanda uses 100 N of force to push a lawnmower around her lawn. If she mows 20 rows measuring 30 meters each, how much work does she do?
- A. 3,000 Nâ‹…m
- B. 6,000 Nâ‹…m
- C. 60,000 Nâ‹…m
- D. The answer cannot be determined from the information given.
Correct Answer: C
Rationale: The work done by Amanda pushing the lawnmower is calculated by multiplying the force applied (100 N) by the distance over which the force is applied (the total distance mowed). Since Amanda mows 20 rows, each measuring 30 meters, the total distance mowed is 20 rows x 30 meters/row = 600 meters. Therefore, the work done is 100 N x 600 m = 60,000 Nâ‹…m. Option A and B are incorrect as they do not account for the total distance mowed. Option D is incorrect as the work done can be accurately calculated based on the information provided.
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Viscosity, μ, is a transport property of a fluid that reflects its:
- A. Inertia
- B. Resistance to flow
- C. Compressibility
- D. Buoyancy generation
Correct Answer: B
Rationale: Viscosity refers to a fluid's resistance to flow. A fluid with high viscosity (like honey) flows slowly, while a fluid with low viscosity (like water) flows more easily. It is a measure of internal friction in the fluid. Choice A, 'Inertia,' is incorrect as inertia is the tendency of an object to resist changes in its state of motion. Choice C, 'Compressibility,' is incorrect as it refers to the ability of a fluid to be compressed. Choice D, 'Buoyancy generation,' is incorrect as it relates to the upward force exerted by a fluid that opposes the weight of an immersed object.
At which point on a roller coaster does the car have the greatest potential energy?
- A. The start of the ride
- B. The highest peak
- C. The lowest trough
- D. The end of the ride
Correct Answer: B
Rationale: The correct answer is B, the highest peak. At the highest peak of the roller coaster, the car reaches its maximum height above the ground. This point represents the car's greatest potential energy because it has the highest potential to do work due to its elevated position. The potential energy is directly proportional to the height of an object, so the highest point on the roller coaster track corresponds to the car's greatest potential energy. Choices A, C, and D are incorrect because potential energy is highest at the peak due to its elevated position, not at the start of the ride, the lowest trough, or the end of the ride.
The triple point of a substance is the specific temperature and pressure at which all three phases (solid, liquid, and gas) can coexist in thermodynamic equilibrium. Which of the following statements about the triple point is true?
- A. It can vary depending on the container size.
- B. It is a unique point for each pure substance.
- C. The pressure at the triple point can be zero for some substances.
- D. The temperature at the triple point can be above the boiling point of the liquid phase.
Correct Answer: B
Rationale: The triple point is a unique temperature and pressure where all three phases (solid, liquid, and gas) of a pure substance can coexist in equilibrium. It is a constant for each substance and independent of container size. Choice A is incorrect because the triple point is a fixed point regardless of the container size. Choice C is incorrect as the pressure at the triple point is specific for each substance and will not be zero unless the substance has unique properties. Choice D is incorrect since the temperature at the triple point is precisely defined and cannot be above the boiling point of the liquid phase.
As the frequency of a sound wave increases, what else is true?
- A. Its wavelength decreases.
- B. Its wavelength increases.
- C. Its amplitude decreases.
- D. Its amplitude increases.
Correct Answer: A
Rationale: The correct answer is A: 'Its wavelength decreases.' The frequency and wavelength of a sound wave are inversely proportional. As the frequency of a sound wave increases (more oscillations per second), its wavelength decreases. This relationship is described by the formula: Speed of Sound = Frequency x Wavelength. Therefore, to maintain the speed of sound constant, when the frequency increases, the wavelength must decrease. Choices B, C, and D are incorrect because an increase in frequency does not lead to an increase in wavelength or changes in amplitude.
Which mathematical quantity is scalar?
- A. Distance
- B. Velocity
- C. Acceleration
- D. Displacement
Correct Answer: A
Rationale: Distance is a scalar quantity because it has only magnitude and no direction. It is simply the total length of the path travelled by an object. Scalars are quantities that are fully described by their magnitude alone, without any reference to direction. Velocity and acceleration are vector quantities as they have both magnitude and direction. Displacement is also a vector quantity as it is the change in position of an object and includes both magnitude and direction.