The Official Phy103 Practice Test
This test was set up by Oyewole Kolawole David Of Mechatronics Engineering department, Fuoye, to help the 100L students prepare for their Physics Exam
Questions and Answers
- 1.
The pressure at any given point of a non-moving fluid is called the ____________
- A.
Guage Pressure
- B.
Atmospheric Pressure
- C.
Differential Pressure
- D.
Hydrostatic Pressure
Correct Answer
D. Hydrostatic PressureExplanation
Hydrostatic pressure refers to the pressure exerted by a fluid at a certain point due to the weight of the fluid column above it. It is a result of the force of gravity acting on the fluid. This pressure is independent of the shape of the container and is directly proportional to the density of the fluid and the height of the fluid column. In contrast, gauge pressure is the pressure measured relative to atmospheric pressure, differential pressure is the difference in pressure between two points, and atmospheric pressure is the pressure exerted by the Earth's atmosphere.Rate this question:
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- 2.
_________ is the evidence that matter is made up of atoms and particles that are in constant vibration
- A.
Brownian motion
- B.
Accelerated motion
- C.
Bernuolli principle
- D.
Special relativity
Correct Answer
A. Brownian motionExplanation
Brownian motion is the evidence that matter is made up of atoms and particles that are in constant vibration. This phenomenon was first observed by the botanist Robert Brown in 1827 when he observed pollen grains in water under a microscope. He noticed that the pollen grains were constantly moving in a random pattern, which he attributed to the motion of water molecules colliding with the pollen grains. This observation provided strong evidence for the existence of atoms and particles that make up matter and their constant motion.Rate this question:
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- 3.
Mercury melts at ________
- A.
0° - 4°C
- B.
404°C
- C.
-38.829°C
- D.
112°C
Correct Answer
C. -38.829°CExplanation
Mercury has a low melting point, and it is one of the few metals that are liquid at room temperature. The given answer of -38.829°C is correct because it falls within the range of temperatures at which mercury melts.Rate this question:
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- 4.
Bulk Modulus, Pressure, Force, Stress – Which one of these won’t have the same unit as the others?
- A.
Bulk Modulus
- B.
Pressure
- C.
Force
- D.
Stress
Correct Answer
C. ForceExplanation
Bulk modulus, pressure, and stress all have the same unit of force per unit area, which is Newtons per square meter (N/m^2) or Pascal (Pa). However, force is measured in Newtons (N), which is a different unit. Therefore, force does not have the same unit as the others.Rate this question:
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- 5.
Which of the following is true?
- A.
Flow is laminar inside the boundary layer and turbulent outside
- B.
Flow is turbulent inside the boundary layer and laminar outside
- C.
Flow is laminar both inside and outside of the boundary layer
- D.
Flow is turbulent both inside and outside of the boundary layer
Correct Answer
A. Flow is laminar inside the boundary layer and turbulent outsideExplanation
The flow is laminar inside the boundary layer and turbulent outside because the boundary layer is the thin layer of fluid that forms on the surface of an object as it moves through a fluid medium. In this layer, the flow is typically smooth and orderly, known as laminar flow. However, as the fluid moves away from the surface and into the outer region, it becomes more chaotic and turbulent due to the mixing of different layers of fluid. Therefore, the flow is laminar inside the boundary layer and turbulent outside.Rate this question:
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- 6.
The SI unit of Surface tension is ______
- A.
Nm
- B.
N/m
- C.
Kg/cm
- D.
Pa
Correct Answer
B. N/mExplanation
Surface tension is defined as the force per unit length acting parallel to the surface of a liquid. It is measured in Newton per meter (N/m). This unit represents the force required to stretch or break a liquid surface. Therefore, N/m is the correct SI unit for surface tension.Rate this question:
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- 7.
__________ is a pointer for the direction of energy transfer.
- A.
Thermodynamics
- B.
Weight
- C.
Temperature
- D.
Thermocouple
Correct Answer
C. TemperatureExplanation
Temperature is a measure of the average kinetic energy of particles in a substance. In thermodynamics, energy transfer occurs from a higher temperature region to a lower temperature region. Therefore, temperature can be considered as a pointer for the direction of energy transfer.Rate this question:
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- 8.
Which thermometer adopts pressure as its thermometric property?
- A.
Alcohol in gas Thermometer
- B.
Electric Resistance
- C.
Thermocouple
- D.
Constant volume gas thermometer
Correct Answer
D. Constant volume gas thermometerExplanation
A constant volume gas thermometer adopts pressure as its thermometric property. In this type of thermometer, the volume of the gas remains constant while the pressure changes with temperature. As the temperature increases, the gas molecules gain more kinetic energy and collide more frequently with the walls of the container, leading to an increase in pressure. By measuring the pressure, the temperature can be determined accurately.Rate this question:
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- 9.
Which of the following is not a scale used in measuring temperature?
- A.
Centigrade
- B.
Fahrenheit
- C.
Temperature
- D.
None of the above
Correct Answer
C. TemperatureExplanation
The given question asks for a scale that is not used in measuring temperature. The options provided are Centigrade, Fahrenheit, and Temperature. Both Centigrade and Fahrenheit are commonly used scales for measuring temperature. However, "Temperature" itself is not a scale, but rather the concept being measured. Therefore, the correct answer is Temperature.Rate this question:
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- 10.
The scale of 212°F in °C is ___
- A.
89°C
- B.
100°C
- C.
88°C
- D.
68.90°C
Correct Answer
B. 100°CExplanation
The correct answer is 100°C because 212°F is the boiling point of water on the Fahrenheit scale, and 100°C is the boiling point of water on the Celsius scale. The two scales have different intervals, but they intersect at this specific temperature.Rate this question:
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- 11.
Water strider can walk walk on water because
- A.
It's weight is not enough to penetrate the surface
- B.
The Viscosity of the water is High
- C.
The surface tension of water strider is High
- D.
It is not true,
Correct Answer
A. It's weight is not enough to penetrate the surfaceExplanation
The correct answer is that the water strider's weight is not enough to penetrate the surface. Water striders have long, thin legs that distribute their weight over a large surface area, allowing them to effectively distribute their weight and not break the surface tension of the water. This enables them to walk on water. The other options, such as the viscosity of the water or the surface tension of the water strider, are not the main reasons for their ability to walk on water.Rate this question:
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- 12.
In the Zeroth law of thermodynamics, the third body stand for the
- A.
Thermocouple
- B.
Thermodynamics
- C.
Thermostatic body
- D.
Thermometer
Correct Answer
D. ThermometerExplanation
The third body in the Zeroth law of thermodynamics refers to a thermometer. This law states that if two bodies are in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other. A thermometer is used to measure the temperature of a body and can be used as a reference point to determine if two bodies are in thermal equilibrium.Rate this question:
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- 13.
_______ is the part of the universe, we choose to study
- A.
Isolated System
- B.
Thermodynamic cycle
- C.
System
- D.
Surrounding
Correct Answer
C. SystemExplanation
The correct answer is "System". In the context of the question, a system refers to the part of the universe that we choose to study. It can be a specific object or a group of objects that we are interested in analyzing or observing. The system is usually defined by boundaries that separate it from its surroundings. By focusing on the system, we can study its properties, behavior, and interactions with its surroundings.Rate this question:
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- 14.
For an isolated system
- A.
Neither the mass nor energy can transfer between the system and the surrounding
- B.
The Thermometer is always stagnant
- C.
There is no acceleration
- D.
Entropy
Correct Answer
A. Neither the mass nor energy can transfer between the system and the surroundingExplanation
In an isolated system, neither the mass nor energy can transfer between the system and the surroundings. This means that the total mass and energy within the system remain constant. The system is completely self-contained and does not interact with its surroundings in terms of mass or energy exchange. Therefore, any changes occurring within the system are solely due to internal processes and interactions.Rate this question:
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- 15.
Which of the laws of thermodynamics defines entropy
- A.
Zeroth
- B.
First
- C.
Second
- D.
Third
Correct Answer
C. SecondExplanation
The second law of thermodynamics defines entropy. Entropy is a measure of the disorder or randomness in a system. According to the second law, the entropy of an isolated system always increases or remains constant over time. This law helps to explain why certain processes occur spontaneously in one direction but not in the reverse direction. It also provides insights into the efficiency of energy conversion and the limitations of heat engines.Rate this question:
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- 16.
First law of thermodynamics deals with
- A.
Conservation of mass
- B.
Conservation of momentum
- C.
Conservation of energy
- D.
Conservation of pressure
Correct Answer
C. Conservation of energyExplanation
The first law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another. This principle is known as the conservation of energy. It means that the total amount of energy in a closed system remains constant. This law is fundamental in understanding the behavior of energy in various thermodynamic processes and systems.Rate this question:
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- 17.
The equation for the average kinetic energy is_________
- A.
0.5KT
- B.
1.5KT
- C.
3.5KT
- D.
3.2KT
Correct Answer
B. 1.5KTExplanation
The equation for the average kinetic energy is 1.5KT. This is derived from the equation for the average kinetic energy of a gas molecule, which is equal to (3/2)KT, where K is the Boltzmann constant and T is the temperature in Kelvin. The factor of 3/2 arises from the equipartition theorem, which states that each degree of freedom of a gas molecule contributes (1/2)KT to its average kinetic energy. Therefore, for a gas molecule with three degrees of freedom, the average kinetic energy is (3/2)KT, which simplifies to 1.5KT.Rate this question:
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- 18.
What is the dimension of strain
- A.
L x L
- B.
It's dimensionless
- C.
M X L X T
- D.
M/L
Correct Answer
B. It's dimensionlessExplanation
The correct answer is "It's dimensionless" because strain is defined as the ratio of the change in length or shape of an object to its original length or shape. Since it is a ratio, it does not have any units and is therefore dimensionless.Rate this question:
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- 19.
An object has a mass of 10kg and a length of 4m, given that the cross-sectional area of the object is 32.5m^2, Now calculate the density of the object
- A.
0.77kg/m^3
- B.
0.077kg/m^3
- C.
7.077kg/m^3
- D.
0.0077kg/m^3
Correct Answer
B. 0.077kg/m^3Explanation
The density of an object is calculated by dividing the mass of the object by its volume. In this case, the mass of the object is given as 10kg. To calculate the volume of the object, we need to multiply the cross-sectional area of the object by its length. The cross-sectional area is given as 32.5m^2 and the length is given as 4m. Multiplying these values together gives us a volume of 130m^3. Dividing the mass (10kg) by the volume (130m^3) gives us a density of 0.077kg/m^3.Rate this question:
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- 20.
A body weighs 0.3N in air, 0.25N when fully immersed in water and 0.27N when fully immersed in a liquid. Calculate its loss of weight in water
- A.
0.05N
- B.
0.003N
- C.
0.6N
- D.
1.3N
Correct Answer
A. 0.05NExplanation
When the body is fully immersed in water, it experiences an apparent loss of weight equal to the weight of the water it displaces. This is known as the buoyant force. The difference in weight between the body in air and the body in water is 0.05N, which represents the loss of weight in water.Rate this question:
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- 21.
A hydraulic press contains 0.25m^3 of oil find the decrease in the volume of the oil when it's subjected to a pressure increase (P' - P) = 1.6 x 10 ^7 Pa. The bulk Modulus of the oil is 5.0GigaPa
- A.
0.6796
- B.
0.0008
- C.
0.00008
- D.
0.008
Correct Answer
B. 0.0008Explanation
The decrease in volume of the oil can be calculated using the formula: ΔV = -V(ΔP/B), where ΔV is the change in volume, V is the initial volume, ΔP is the change in pressure, and B is the bulk modulus. Plugging in the given values, ΔP = 1.6 x 10^7 Pa and B = 5.0 GigaPa (5.0 x 10^9 Pa), we can calculate ΔV = -0.25m^3 * (1.6 x 10^7 Pa / 5.0 x 10^9 Pa) = -0.0008m^3. Since the question asks for the decrease in volume, the answer is 0.0008m^3.Rate this question:
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- 22.
A uniform cylindrical wooden block floats in water with 1/3 of its height above the water level. In a liquid of a relative density 0.8, what fraction of its height will be above the liquid
- A.
1/6v
- B.
1/7v
- C.
1/4v
- D.
1/3v
Correct Answer
A. 1/6vExplanation
When a uniform cylindrical wooden block floats in water, the fraction of its height above the water level is equal to the fraction of its volume that is above the water level. Since the block floats, its weight is balanced by the buoyant force, which is equal to the weight of the water displaced by the block. In this case, 1/3 of the block's height is above the water level, so 1/3 of its volume is also above the water level. When the same block is placed in a liquid with a relative density of 0.8, the buoyant force will still balance its weight. Therefore, the fraction of its height above the liquid will also be 1/3, which is equal to 1/6 of its volume.Rate this question:
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- 23.
When a leaf floats on the surface of water, its able to float because of the force on the surface of the water, and this force is called
- A.
Young modulus
- B.
Density
- C.
Viscosity
- D.
Surface Tension
Correct Answer
D. Surface TensionExplanation
When a leaf floats on the surface of water, it is able to do so because of the force on the surface of the water. This force is known as surface tension. Surface tension is caused by the cohesive forces between the water molecules at the surface, which create a "skin" or "film" on the water's surface. This surface tension allows objects with low density, like the leaf, to float on top of the water instead of sinking.Rate this question:
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- 24.
Which among the following is an assumption of Hagen-Poiseuille equation?
- A.
Fluid is compressible
- B.
Fluid is uniform
- C.
Fluid is laminar
- D.
Fluid is turbulent
Correct Answer
C. Fluid is laminarExplanation
The Hagen-Poiseuille equation is used to describe the flow of a viscous fluid through a cylindrical pipe. One of the assumptions of this equation is that the fluid flow is laminar, meaning that the fluid particles move in parallel layers without any mixing or turbulence. This assumption allows for a simplified mathematical model to be used to calculate the flow rate and pressure drop in the pipe. If the fluid flow is turbulent, the Hagen-Poiseuille equation would not be applicable.Rate this question:
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- 25.
Which of the following affects surface tension
- A.
Thermodynamics
- B.
Type of force
- C.
Impurity
- D.
Pressure
Correct Answer
C. ImpurityExplanation
Impurity affects surface tension. Surface tension is the property of a liquid that allows it to resist an external force and minimize its surface area. When impurities are present in the liquid, they disrupt the cohesive forces between the liquid molecules, reducing the surface tension. This is because the impurities interfere with the attractive forces that hold the liquid molecules together at the surface, causing the surface tension to decrease.Rate this question:
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- 26.
A student using a circular loop of wire and a pan of soapy water produces a bubble whose radius is 1mm. The surface tension of the soapy water is [¥= 0.025N/m] determine the pressure difference between the inside and outside of the pan.
- A.
1000N/m^2
- B.
100N/m
- C.
100N/m^2
- D.
100N/m
Correct Answer
C. 100N/m^2Explanation
The pressure difference between the inside and outside of the pan can be determined using the formula for pressure difference in a soap bubble: ΔP = 4T/r, where ΔP is the pressure difference, T is the surface tension, and r is the radius of the bubble. Substituting the given values, we get ΔP = 4(0.025)/(0.001) = 100 N/m^2.Rate this question:
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- 27.
Pyrometer is best used to measure
- A.
Very low temperatures
- B.
Low temperatures
- C.
Room temperature
- D.
High temperature
Correct Answer
D. High temperatureExplanation
A pyrometer is best used to measure high temperatures. This is because a pyrometer is a type of thermometer that is specifically designed to measure temperatures above the range of traditional thermometers. It uses the principle of thermal radiation to determine the temperature of an object or a surface. Pyrometers are commonly used in industrial settings, such as in metalworking or glass manufacturing, where high temperatures need to be accurately measured. They are not suitable for measuring very low temperatures or room temperature, as they are not designed for such applications.Rate this question:
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- 28.
A deuterium nuclei fusion reaction will occur provided that the nuclei possesses an average kinetic energy of at least 0.72Mev what is the temperature required for nuclear fusion to take place in the deuterium?
- A.
2.17 x 10^47
- B.
2.07 x 10^-23
- C.
3 x 10^8
- D.
0.772 x 10^7
Correct Answer
A. 2.17 x 10^47 -
- 29.
Which of the following is not a basic type of stress
- A.
Volumetric stress
- B.
Shear stress
- C.
Compressive stress
- D.
Tensile stress
Correct Answer
A. Volumetric stressExplanation
Volumetric stress refers to the stress that occurs when a material is subjected to a change in volume. It is not considered a basic type of stress because it is a combination of normal and shear stresses acting on all surfaces within the material. The other options, shear stress, compressive stress, and tensile stress, are all fundamental types of stress that occur in different ways and have distinct characteristics.Rate this question:
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- 30.
Hooke’s law is applicable within what limit?
- A.
Fracture limit
- B.
Elastic limit
- C.
Ultimate strength
- D.
Plastic limit
Correct Answer
B. Elastic limitExplanation
Hooke's law states that the extension of a spring is directly proportional to the force applied to it, as long as the elastic limit of the material is not exceeded. This means that within the elastic limit, the material will return to its original shape and size after the force is removed. Therefore, the correct answer is the elastic limit.Rate this question:
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- 31.
In liquids in order to measure the viscosity of fluid experimentally we consider the variation of shear stress with respect to what property?
- A.
Strain.
- B.
Shear strain
- C.
Rate of shear strain
- D.
None of the above
Correct Answer
C. Rate of shear strainExplanation
The correct answer is "Rate of shear strain". In order to measure the viscosity of a fluid experimentally, we consider the variation of shear stress with respect to the rate of shear strain. Viscosity is a measure of a fluid's resistance to flow, and it is determined by how the fluid responds to an applied shear stress. By measuring the rate of shear strain, we can determine how quickly the fluid deforms under the applied stress, which allows us to calculate its viscosity.Rate this question:
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- 32.
___________ is the condition of a system at an instant of time.
- A.
Process
- B.
State
- C.
System
- D.
Thermocycle
Correct Answer
B. StateExplanation
The term "state" refers to the condition of a system at a specific moment in time. It describes the values of all relevant variables that define the system's behavior and characteristics. In the context of this question, "state" is the most appropriate answer as it accurately captures the concept of the condition of a system at an instant of time.Rate this question:
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- 33.
A cubic tank is completely filled with water. What will be the ratio of the hydrostatic force exerted on the base and on any one of the vertical sides?
- A.
1:1
- B.
2:1
- C.
1:2
- D.
3:2
Correct Answer
B. 2:1Explanation
The ratio of the hydrostatic force exerted on the base and on any one of the vertical sides of a cubic tank filled with water is 2:1. This is because the hydrostatic force on the base is directly proportional to the area of the base, while the force on the vertical sides is directly proportional to the height. Since the height of the tank is equal to the length of one side, the ratio of the forces will be 2:1.Rate this question:
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- 34.
Which among the following is the formula for Gibbs free energy?
- A.
H-T∆S
- B.
T∆S
- C.
H - T
- D.
H - T
Correct Answer
A. H-T∆SExplanation
The formula for Gibbs free energy is H - T∆S. This formula represents the change in free energy of a system during a chemical reaction or physical process. H represents the enthalpy, which is the heat absorbed or released during the process. T represents the temperature in Kelvin, and ∆S represents the change in entropy. By subtracting the product of temperature and change in entropy from the enthalpy, we can calculate the Gibbs free energy.Rate this question:
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- 35.
Compressible flow is a flow that deals with ______
- A.
Fluid temperature
- B.
Fluid pressure
- C.
Fluid density
- D.
Fluid geometry
Correct Answer
C. Fluid densityExplanation
Compressible flow is a flow that deals with fluid density. In compressible flow, the density of the fluid changes significantly due to changes in pressure and temperature. This type of flow is observed in gases, where the molecules are far apart and can be compressed or expanded easily. The density of the fluid plays a crucial role in determining the behavior of the flow, including the speed of the flow, the formation of shock waves, and the propagation of disturbances through the fluid.Rate this question:
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- 36.
_________ Law of thermodynamics states that if two systems are each equal in temperature to a third, they are equal in temperature to each other
- A.
Zeroth
- B.
First
- C.
Second
- D.
Third
Correct Answer
A. ZerothExplanation
The Zeroth Law of thermodynamics states that if two systems are each equal in temperature to a third, then they are equal in temperature to each other. This law establishes the concept of temperature and provides a basis for measuring and comparing temperatures. It implies that temperature is a property that can be shared and transferred between systems, allowing for the establishment of thermal equilibrium. The Zeroth Law is fundamental in understanding the behavior of systems in thermal contact and forms the basis for the other laws of thermodynamics.Rate this question:
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- 37.
The collision of gas molecules among themselves is
- A.
Perfectly inelastic
- B.
Perfectly elastic
- C.
Expandable
- D.
Compressed
Correct Answer
B. Perfectly elasticExplanation
In a perfectly elastic collision, the gas molecules collide without any loss of kinetic energy. This means that the total kinetic energy before the collision is equal to the total kinetic energy after the collision. In such collisions, the gas molecules rebound off each other with the same speed and energy as before the collision. This is in contrast to perfectly inelastic collisions, where the gas molecules stick together and lose kinetic energy, and to expandable or compressed collisions, which do not describe the nature of the collision itself.Rate this question:
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- 38.
Gas molecules obeys Newton law
- A.
True
- B.
False
- C.
All of the above
- D.
None of the above
Correct Answer
A. TrueExplanation
Gas molecules obey Newton's law of motion, which states that an object in motion will remain in motion unless acted upon by an external force. This means that gas molecules will continue to move in a straight line at a constant velocity unless influenced by an external force, such as collisions with other molecules or the walls of a container. Therefore, the statement "Gas molecules obey Newton's law" is true.Rate this question:
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- 39.
________ materials can easily be broken or cracked
- A.
Ductile
- B.
Brittle
- C.
Malleable
- D.
Compressible
Correct Answer
B. BrittleExplanation
Brittle materials can easily be broken or cracked. Unlike ductile or malleable materials, which can be stretched or bent without breaking, brittle materials lack the ability to deform plastically. They have low ductility and are prone to fracture when subjected to stress, making them fragile and easily breakable. Compressibility refers to the ability of a material to be reduced in volume under pressure and is not related to brittleness.Rate this question:
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- 40.
________ Law states that provided the elastic limit of an elastic material is not exceeded, the force applied is directly proportional to the extension
- A.
Hooke’s law
- B.
Charles law
- C.
String law
- D.
Law of extension
Correct Answer
A. Hooke’s lawExplanation
Hooke's law states that the force applied to an elastic material is directly proportional to the extension or deformation of the material, as long as the elastic limit is not exceeded. This means that if you apply a force to stretch or compress an elastic material, the amount of extension or compression will be directly proportional to the amount of force applied. Hooke's law is commonly used to describe the behavior of springs and other elastic materials.Rate this question:
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