when a small object floats on the surface of a liquid the surface tension creates a

HESI A2

HESI A2 Physics Quizlet

1. When a small object floats on the surface of a liquid, the surface tension creates a:

A. Buoyant force acting upwards
B. Pressure difference causing sinking
C. Drag force opposing motion
D. Restoring force towards equilibrium

Correct answer: D

Rationale: Surface tension creates a restoring force that holds the object on the surface. The liquid's surface behaves like a stretched membrane, and when disturbed, it tends to return the object to its original position, creating a restoring force. The other choices are incorrect: A buoyant force acts on objects submerged in a fluid, not floating on the surface; pressure differences usually affect sinking objects, not floating ones; drag force is a resistance force that opposes motion, not related to surface tension.

2. In a static fluid, pressure (P) at a depth (h) is governed by the hydrostatic equation:

A. P = ρgh
B. P = γh
C. P = μgh
D. P = bh

Correct answer: A

Rationale: The correct formula for the pressure at a certain depth in a fluid according to the hydrostatic equation is P = ρgh. Here, ρ represents the fluid's density, g is the gravitational acceleration, and h is the depth. This formula shows that pressure increases linearly with the density of the fluid, the acceleration due to gravity, and the depth. Choices B, C, and D are incorrect because they do not accurately represent the relationship between pressure, density, gravitational acceleration, and depth in a static fluid.

3. In an electrically neutral atom, the number of:

A. Electrons is equal to protons
B. Protons is equal to neutrons
C. Neutrons are always greater than protons
D. Electrons are always less than protons

Correct answer: A

Rationale: In an electrically neutral atom, the number of electrons is equal to the number of protons. Electrons carry a negative charge, protons carry a positive charge, and neutrons are neutral. Since the atom is electrically neutral, the positive charge of the protons must balance the negative charge of the electrons, making the numbers of electrons and protons equal. Choice B is incorrect because protons are not equal to neutrons in an atom. Choice C is incorrect because neutrons are not always greater than protons, and choice D is incorrect because electrons are not always less than protons in an atom.

4. In terms of electrical conductivity, semiconductors fall between

A. Conductors and insulators
B. Conductors and superconductors
C. Insulators and dielectrics
D. Superconductors and insulators

Correct answer: A

Rationale: Semiconductors have electrical conductivities that lie between those of conductors (high conductivity) and insulators (low conductivity). This positioning makes choice A, 'Conductors and insulators,' the correct answer. Choice B, 'Conductors and superconductors,' is incorrect because superconductors have perfect conductivity, not intermediate like semiconductors. Choice C, 'Insulators and dielectrics,' is incorrect because dielectrics are a type of insulator, so it doesn't show the progression from high to low conductivity. Choice D, 'Superconductors and insulators,' is incorrect because superconductors have the highest conductivity, opposite to the role of semiconductors.

5. 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.