## LenAcad

Questions on Physics

# A measurement of how much the velocity of an object changes with time is termed _____. A. Displacement B. Acceleration C. Speed D. Momentum E. Velocity-Time graph F. Average velocity ANSWER: Acceleration Acceleration is defined as the rate of change of velocity. Acceleration is also defined as the measurement of how much the velocity of an object changes with time. Acceleration = Change in velocity/Change in time   If an object changes velocity after a fixed amount of time, then such acceleration is said to be constant (that is: constant acceleration).     We also have the concept of average acceleration in motion. Average acceleration is the total change in velocity over a period of time, divided by the duration of that period. Acceleration is a vector quantity and its Standard International (SI) unit is meter per second (m/s) or meter per second square (m/s2). Which of the following differentiates velocity from speed? A. Distance B. Time C. Momentum D. Inertia E. Direction F. Distance and Time ANSWER: Direction The direction in which an object is moving is what differentiates velocity from speed. In short, velocity is defined as speed in a given direction. It is also defined as the rate of change of displacement. Please read more on velocity and acceleration here FA = -FB FA is the action force while FB is the reaction force. The above statement expresses _____. A. Force and Acceleration B. Force and Gravity C. Force and Momentum D. Newton's first law of motion E. Newton's second law of motion F. Newton's third law of motion ANSWER: Newton's third law of motion Newton's third law states that action and reaction are equal and opposite. According to the third law of motion, if a body 'A' exerts a force FA on another body 'B', body B will in return exert an equal and opposite force FB on body A. The forces FA and FB are therefore equal in magnitude but opposite in direction. Please read more on Newton's laws of motion here A natural force that pulls a body towards the center of the earth is termed _____. A. Centripetal force B. Centrifugal force C. Black hole D. Average acceleration E. Gravity F. Momentum ANSWER: Gravity Gravity is defined as a natural force that pulls a body towards the center of the earth or another physical body having a greater mass. The effects of gravity on the earth and it's inhabitants are crucial for life. Please read more on the effects or importance of gravity here A Greek letter that expresses density is _____. A. Alpha_d B. Beta_d C. Theta_d D. rho E. dho F. dhr ANSWER: rho rho is a Greek letter that expresses density. Density is defined as the mass of a unit volume of a substance. It's standard international (SI) unit is kg/m3​​​. A glass of water has a higher density than an exact glass of oil. A. True B. False ANSWER: True A glass of water has a higher density than an exact glass of oil. This is true because water has more weight (is denser) than oil. For this reason, if oil is poured on water, it floats on it because it's lighter. It is noteworthy to state that water has a density of 1000kg/m3 while oil has got a lesser value. Please read more on density here An 🍎 apple 🍎 falling from a tree has an unbalanced force. A. True B. False ANSWER: True An apple falling from a tree has an unbalanced force. Think of it this way: When forces from different directions act on an object and consequently bring about the object's movement, then such forces are unbalanced. If the forces were to be balanced, then the object will remain in a static position. Please read more on force and motion here Force is a quantity measured in _____. A. Kilogram B. Gravity C. Incandescence D. Meter per second square (ms-1) E. Mole F. Newton ANSWER: Newton Force is a quantity measured in Newton. This is in honor of Sir Isaac Newton for the great work he had done on motion and force.  Please read more on the concept of force and motion here Heat transfer indicates two systems of varying temperatures and will always be transferred from a region with lower temperature to another with higher temperature. A. True B. False ANSWER: False Heat transfer indicates two systems of varying temperatures and will always be transferred from a region with higher temperature to another with lower temperature. Understand that heat is always transferred from a higher temperature region to a lower temperature region. To better understand the processes of heat transfer, a knowledge on the movement of particles (in matter) is required. Please read more on heat transfer and particle movements in matter here Heat can be created. A. True B. False ANSWER: False Heat cannot be created nor destroyed. Also it cannot be lost. This is true because it's a form of energy (heat energy). According to the first law of thermodynamics, energy can neither be created nor destroyed but can be transferred from one form to another. You can read more on the concept of temperature and heat here Temperature is defined as the measure or ability of an object or substance to transfer heat energy to another object or substance. A. True B. False ANSWER: True Although temperature is popularly defined as the degree of hotness or coldness of a substance or an object with reference to some standard value; the (above definition) in the question is also correct. The above definition is true because heat is never static, thus it is always transferred. Please read more on temperature and heat here Which of the following statement is incorrect concerning gravity? A. It is a natural force of attraction B. The earth is spherical in shape and we don't fall off it due to gravity C. The amount of gravity is the same all around the spherical earth D. Earth's gravity affects the satellites E. Gravity is affected by size and closeness of objects F. In an ideal space environment, gravity is absent ANSWER: The amount of gravity is the same all around the spherical earth The amount of gravity is not the same all around the spherical earth. It is slightly stronger on earth surfaces with a greater mass underground than those with lesser masses. Please read more on gravity here If two bodies are in thermal equilibrium with another body, then they are also in equilibrium with each other. The above statement is the _____ law of thermodynamics. A. Zeroth B. First C. Second D. Third E. Fourth F. Fifth ANSWER: Zeroth The Zeroth Law of Thermodynamics states that if two bodies are in thermal equilibrium with another body, then they are also in equilibrium with each other. Let's assume we have three bodies named X, Y and Z respectively. According to the zeroth law of thermodynamics, if X=Y and Z=Y, then X=Z. Please read more on the Zeroth Law of Thermodynamics here Which of the following is a derived unit? A. Kelvin B. Meter C. Newton D. Candela E. Mole F. Ampere ANSWER: Newton Newton (N) is a derived unit for the quantity -> force. Recall that force is a derived quantity. In fact, it's derived from the product of mass and acceleration. This therefore implies that kilogram per second square (kg/s2) is also a derived unit of force. In summary, the derived unit of force is kg/s2 or N Please read more on derived units here The following are fundamental quantities except _____. A. Power B. Electric Current C. Amount of Substance D. Temperature E. Time F. Length ANSWER: Power Power is not a fundamental quantity. (It is a derived unit). Fundamental quantities are quantities dependent only on themselves and as a result, their units cannot be changed; nor is related to another fundamental unit. Fundamental quantities are 7 in number. Please read more on fundamental quantities here When a car moves at a speed in a given direction, its referred to as _____. A. Speed B. Velocity C. Momentum D. Inertia E. Acceleration F. Constant Acceleration ANSWER: Velocity Velocity is simply speed in a given direction. It's also defined as the rate of change of displacement. Note: The Standard International (SI) unit of velocity is meter per second (m/s). As an instance, if a bus moves at a speed of 10m/s in the nothern direction and suddenly turns into the western direction, moving with a different speed or even the same speed; then that's velocity. In the above instance, velocity comes into action because the direction of movement changed regardless the speed. Velocity is a vector quantity because it has both magnitude and direction. Please read on Motion and Speed here. The rate of change of momentum is proportional to the applied force and will take place in the direction of that force. The above statement is attributed to _____. A. Albert Einstein B. Isaac Newton C. Galileo Galilei D. Neils Bohr E. Ernest Rutherford F. Marie Curie Answer: Isaac Newton The rate of change of momentum is proportional to the applied force and will take place in the direction of that force is attributed to Sir Isaac Newton; and that's his second law of motion. Other laws of motion stated by Newton are: An object will continue in its state of rest while an object in uniform motion will continue in a straight line, unless an external force acts on it - Newton's first law of motion To every action, there is an equal and opposite reaction - Newton's third law of motion The Law of Inertia is also referred to as _____. A. 1st Law of Thermodynamics B. 2nd Law of Thermodynamics C. 3rd Law of Thermodynamics D. Newton's 1st Law of Motion E. Newton's 2nd Law of Motion F. Newton's 3rd Law of Motion ANSWER: Newton's 1st Law of Motion Newton's 1st Law of Motion, also called the Law of Inertia states that: A body at rest will continue to be in a state of rest while a body in uniform motion will continue in a straight line; unless an external force acts upon it. Please read on the Laws of Motion here The process whereby the velocity of an object increases and decreases over a period of time is best associated with the term _____. A. Speed B. Velocity C. Momentum D. Constant Velocity E. Acceleration F. Average Velocity ANSWER: Acceleration Acceleration is simply defined as the rate of change of velocity. For instance, when one rides a bicycle, they begin slowly. Along the journey, they increase the push on the pedals, thus increasing the speed of the bicycle. When they are about to make a turn along their path, the speed of the bicycle will be reduced. Finally, towards the end of the journey, the rider slows down and eventually stops. Notice in the above instance that the rider makes a turn along their path. This change in direction refers to velocity. The above instance also shows an increase and decrease in velocity; and this is the concept of acceleration. In fact, acceleration can be positive or negative. Note: In Physics we use the term acceleration to describe both positive and negative acceleration. Acceleration is a vector quantity because it has both magnitude and direction. Please read on Speed, Velocity and Acceleration here. The rate of motion is best referred to as _____. A. Speed B. Velocity C. Momentum D. Inertia E. Acceleration F. Constant Velocity ANSWER: Speed Speed is simply the rate of motion. It can also be defined as the rate of change of distance. Note: When we use the term 'rate' to describe an activity; it simple implies the time expended on such activity. For instance, If a sprinter runs a 100m (meter) track for 9.6s (seconds); that's simply his speed. Think of speed as a distance (in meter) covered under a specific time (in seconds) From the above points, it can be deduced that the Standard International (SI) unit for speed is meter per second (m/s) Speed is a scaler quantity since it has only magnitude. It has NO direction. Please read on Motion, Speed, Velocity and Acceleration here. \$(".reglogin").hide(); \$(document).ready(function() { \$(".see1").click(function() { \$(this).next().slideToggle('slow'); }); }); \$(".answer").hide(); \$(document).ready(function() { \$(".see").click(function() { \$(this).next().slideToggle('slow'); }); });

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