Nursing Elites

1. In the mechanical power equation P = E / t, power is measured in ___________.

• A. ohms
• B. Joules
• C. volts
• D. watts

Correct answer: D

Rationale: In the mechanical power equation P = E / t, power is measured in watts. Watts are the standard unit of power in the International System of Units (SI), named after the Scottish engineer James Watt. Watts are defined as joules per second, reflecting the rate at which energy is transferred or converted. Ohms (choice A) are the unit of electrical resistance, Joules (choice B) are the unit of energy, and volts (choice C) are the unit of electric potential difference. Therefore, the correct answer is watts as it directly relates to power in the given equation.

2. 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.

3. In physics, the relationship between acceleration and force is expressed in ___________.

• A. Newton’s first law of motion
• B. Newton’s second law of motion
• C. Newton’s third law of motion
• D. none of Newton’s laws of motion

Correct answer: B

Rationale: The relationship between acceleration and force is expressed in Newton’s second law of motion. This law states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the object's mass. Mathematically, this relationship is represented as F = ma, where F is the force, m is the mass of the object, and a is the acceleration. Choice A, Newton’s first law of motion, also known as the law of inertia, states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. Choice C, Newton’s third law of motion, states that for every action, there is an equal and opposite reaction, focusing on the interaction between two objects. Choice D is incorrect because the relationship between acceleration and force is indeed described by one of Newton’s laws of motion, specifically the second law.

4. A pitcher throws a 45-g baseball at a velocity of 42 meters per second. What is the ball’s momentum?

• A. 0.189 kg⋅m/s
• B. 1.89 kg⋅m/s
• C. 1.07 kg⋅m/s
• D. 0.93 kg⋅m/s

Correct answer: B

Rationale: Momentum is calculated by multiplying mass (in kg) by velocity (in m/s). The mass of the baseball is 0.045 kg (45 grams converted to kg), and the velocity is 42 m/s. Momentum = 0.045 kg × 42 m/s = 1.89 kg⋅m/s. Therefore, the correct answer is 1.89 kg⋅m/s. Choice A is incorrect as it incorrectly converts the mass from grams to kg. Choice C and D are incorrect due to calculation errors.

5. In an adiabatic process, there is:

• A. No heat transfer (Q = 0) between the system and the surroundings.
• B. Isothermal compression or expansion (constant temperature).
• C. Constant pressure throughout the process (isobaric process).
• D. No change in the system's internal energy (energy is conserved according to the first law).

Correct answer: A

Rationale: In an adiabatic process, choice A is correct because adiabatic processes involve no heat transfer between the system and its surroundings (Q = 0). This lack of heat transfer is a defining characteristic of adiabatic processes. Choices B, C, and D do not accurately describe an adiabatic process. Choice B refers to an isothermal process where temperature remains constant, not adiabatic. Choice C describes an isobaric process with constant pressure, not specific to adiabatic processes. Choice D mentions the conservation of energy but does not directly relate to the absence of heat transfer in adiabatic processes.

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