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

HESI A2

HESI A2 Physics

1. 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.

2. Fluid dynamics is a subfield of fluid mechanics concerned with:

A. Equilibrium properties of fluids at rest (Fluid Statics)
B. The motion and behavior of fluids under various conditions
C. Phase transitions of fluids between liquid, gas, and solid states
D. Engineering applications of fluids (related but broader than fluid dynamics)

Correct answer: B

Rationale: Fluid dynamics is the study of fluids in motion and their behavior under different conditions, including how they flow, mix, and interact with their surroundings. It focuses on the dynamic aspects of fluids rather than their static properties when at rest, which is the realm of fluid statics. Phase transitions of fluids between liquid, gas, and solid states are more related to thermodynamics than fluid dynamics. While engineering applications involve fluid dynamics, the field itself is more specialized in studying the movement and behavior of fluids.

3. When a fluid flows past a solid object, a thin layer of fluid adheres to the object's surface due to:

A. Buoyancy
B. Bernoulli's principle
C. Boundary layer effect
D. Surface tension minimization

Correct answer: C

Rationale: The boundary layer effect occurs when a thin layer of fluid near the surface of a solid adheres to it due to viscosity. This layer experiences a velocity gradient as the fluid farther from the surface moves faster, while the fluid closest to the surface is nearly stationary.

4. A 3-volt flashlight uses a bulb with 60-ohm resistance. What current flows through the flashlight?

A. o.05 amp
B. o.5 amp
C. 1.8 amp
D. 18 amp

Correct answer: A

Rationale: : Using Ohm's Law, I = V / R: I = 3 / 60 = 0.05 amp. So, the correct current is 0.05 amp.

5. 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.