The Official Phy101 CBT Practice

Fundamental quantities are known to be independent because they are the basic physical quantities that cannot be derived from any other quantities. They are considered as the building blocks for all other quantities. Examples of fundamental quantities include length, mass, time, electric current, temperature, amount of substance, and luminous intensity. These quantities are independent and are used to define other derived quantities and units.

The unit of angular acceleration is rad/sec because angular acceleration measures the rate at which an object's angular velocity changes over time. Angular velocity is measured in radians per second (rad/sec), and since angular acceleration is the change in angular velocity per unit of time, it is also measured in radians per second (rad/sec).

Random motion refers to the movement of an object without any specific direction or pattern. It occurs when the object's motion is unpredictable and changes constantly. In random motion, the object moves in various directions and at different speeds, making it difficult to determine its exact path. This type of motion can be observed in the movement of particles in a gas or the Brownian motion of small particles in a liquid.

The quantity Mgh has the same dimensions as kinetic energy, 1/2mv^2. This is because both Mgh and 1/2mv^2 have the dimensions of mass times distance squared divided by time squared. In Mgh, M represents mass, g represents acceleration due to gravity, and h represents height. Therefore, Mgh is the correct answer.

The principle of relativity is the correct answer because it states that the laws of physics are the same in all inertial reference frames. This means that no matter how fast or in what direction an observer is moving, the fundamental laws of nature remain unchanged. This principle was first formulated by Galileo and later expanded upon by Einstein in his theory of special relativity. It is a fundamental concept in modern physics and has been confirmed by numerous experiments and observations.

Centripetal force is the correct answer because it is the force that acts towards the center of a circular path, keeping an object moving in that path. It is responsible for maintaining the object's acceleration and preventing it from moving in a straight line tangent to the circle. Centrifugal force, on the other hand, is a perceived force that appears to push objects away from the center of rotation, but it is actually a result of the object's inertia. Oscillatory force is not a recognized term in physics.

Inertia is the property of a body to remain at rest or to continue moving in a straight line. It is the resistance of an object to any change in its state of motion. This means that an object at rest will stay at rest, and an object in motion will continue moving with the same speed and direction, unless acted upon by an external force. Inertia is a fundamental concept in physics and is related to the mass of an object.

A rigid body is one for which the distance between any two points of the body remains the same when the body is translated or rotated. This means that no matter how the body is moved or turned, the distances between all points on the body remain constant. This property is often observed in solid objects such as a metal rod or a wooden block, where the shape and size of the object do not change regardless of its position or orientation.

The correct answer is trajectory. In projectile motion, the trajectory refers to the path that a projectile follows through the air. It is the curved path that results from the combination of the projectile's initial velocity and the force of gravity acting on it. The trajectory can be described using mathematical equations and can be influenced by factors such as the angle of projection and the initial velocity of the projectile.

Dr. Hammed Shakirudeen is the correct answer because the question asks for the head of the Physics Department in Federal University Oyè Ekiti. Since Dr. Hammed Shakirudeen is the only option given with a title of "Dr." and the others are either listed as "Proffesor" or "Dr." without a specific department mentioned, it can be inferred that Dr. Hammed Shakirudeen is the head of the Physics Department.

The correct answer is Kinematics. Kinematics is the branch of physics that deals with the motion of objects without considering the forces causing the motion. It focuses on describing the position, velocity, and acceleration of objects, as well as their trajectories and time dependence. In this context, the question is asking for the branch of physics that specifically deals with the problems and dynamics of motion without referring to any external forces or factors. Therefore, the correct answer is Kinematics.

The range of a projectile is the horizontal distance it travels before hitting the ground. To find the range, we can use the formula: R = (v^2 * sin(2θ)) / g, where R is the range, v is the initial velocity, θ is the angle of projection, and g is the acceleration due to gravity. Plugging in the given values, we get R = (8^2 * sin(2*15))/10 = 3.2. Therefore, the correct answer is 3.2.

The meaning of frame of reference is space. A frame of reference is a coordinate system that is used to describe the position, motion, and properties of objects in space. It provides a point of reference from which measurements and observations can be made. In physics, frames of reference are essential for analyzing the motion of objects and understanding their interactions within a given space.

The speed of light is a fundamental constant in physics and is denoted by the symbol "c". It is approximately equal to 3 x 10^8 meters per second. This value represents the speed at which light travels in a vacuum. It is an important constant in various scientific calculations and is used as a reference point for measuring the speed of other objects or phenomena.

Galilean invariance refers to the principle that the laws of physics are the same in all inertial reference frames. It is named after Galileo Galilei, who made significant contributions to the development of classical mechanics. Galilean relativity is another term used to describe this principle, emphasizing the idea that physical phenomena are relative and independent of the observer's motion. This term highlights the fundamental concept that the laws of physics remain unchanged regardless of the observer's velocity or reference frame.

The correct answer is "Moves 6m every second." This is because the question states that the object moves at a constant speed of 6m/s, which means it covers a distance of 6 meters in every second.

The average velocity is defined as the total displacement covered divided by the total time taken. It represents the overall rate of change of position over a given time interval.

The coefficient of friction is a measure of the frictional force between two surfaces in contact. In this scenario, a block of mass 10kg was moved by a force of 20N. By using Newton's second law (F = ma), we can calculate the acceleration of the block. Then, by using the equation for frictional force (Ff = μN), where N is the normal force, we can solve for the coefficient of friction. Without additional information, we assume that the normal force is equal to the weight of the block (mass x gravity). By plugging in the values, we find that the coefficient of friction is 0.2.

The correct answer is "All the laws of physics are the same in all inertia frame of reference." This answer aligns with the first postulate of Albert Einstein in special relativity, which states that the laws of physics are the same in all inertial frames of reference. This means that the fundamental principles and equations of physics remain unchanged regardless of the frame of reference from which they are observed. This postulate is a foundational concept in understanding the behavior of objects in motion and the consistency of physical laws across different perspectives.

Dimension is the physical entity that can be measured. It refers to the measurable properties of an object or system, such as length, mass, time, temperature, etc. Units are used to quantify these dimensions, while a force is a type of interaction between objects and a system refers to a collection of objects or components working together.

The velocity of a particle can be found by integrating its acceleration over time. In this case, the acceleration is given as 2x^3 + 3x^2. To find the velocity at t=2s, we need to integrate the acceleration function from t=0s to t=2s. After integrating, we get the velocity function as (2/4)x^4 + (3/3)x^3 + C, where C is the constant of integration. Evaluating the velocity function at t=2s, we get (2/4)(2^4) + (3/3)(2^3) + C = 16 + 16 + C = 32 + C. Since the constant of integration is not given, we cannot determine its value. Therefore, the velocity of the particle at t=2s could be any value, and none of the given options can be determined as the correct answer.

The correct answer is "Special relativity". Einstein's two postulates, known as the special theory of relativity, are based on the principles that the laws of physics are the same in all inertial reference frames and that the speed of light in a vacuum is constant for all observers. These postulates revolutionized our understanding of space, time, and the relationship between matter and energy. The equation E=mc^2 is a consequence of special relativity, but it is not one of the two postulates.

Axes define a local space in which the positions of other objects are described. In a coordinate system, axes (such as the X, Y, and Z axes in three-dimensional space) provide a reference framework to measure and describe the position of objects relative to that space. Points, observers, and coordinates are related to describing positions, but axes specifically set up the spatial reference.

Moment of inertia can be defined as the summation of the mass of an object and the square of the perpendicular distance.

The change in momentum of an object can be calculated using the formula change in momentum = force x time. In this case, the force acting on the body is 15N and the time period is 4s. Therefore, the change in momentum is equal to 15N x 4s = 60Ns.

The range of a projectile is given by the formula:

Range = (Speed × Speed × sin 2θ) ÷ Gravity

To get the maximum range, the launch angle is 45 degrees. At this angle, sin 2θ = 1.

So the formula becomes:

Maximum Range = (Speed × Speed) ÷ Gravity

Given the maximum range is 26.4 meters and gravity is 9.8 m/s², we can calculate the speed:

Speed = √(26.4 × 9.8) ≈ 16.2 m/s

Answer: The particle was launched at approximately 16.2 m/s.

When the velocity of an object is doubled, its kinetic energy is quadrupled. This is because kinetic energy is directly proportional to the square of the velocity. Therefore, when the velocity is doubled, the kinetic energy increases by a factor of four.

When the gun releases the bullet, according to the law of conservation of momentum, the total momentum before and after the event should be equal. The momentum of an object is calculated by multiplying its mass by its velocity.
Before the event, the gun and the bullet have a total momentum of 10kg (mass of the gun) multiplied by the unknown velocity of the gun. After the event, the bullet has a momentum of 20g (mass of the bullet) multiplied by 100m/s (speed of the bullet), and the gun has a momentum of 10kg (mass of the gun) multiplied by the recoil velocity.
By equating the total momentum before and after the event, we can solve for the recoil velocity of the gun. In this case, the recoil velocity of the gun is calculated to be 0.2m/s.

The particle is at rest when its velocity is zero. To find the time at which the particle is at rest, we need to find the time when the velocity function, which is the derivative of the position function, equals zero. Taking the derivative of the position function, we get the velocity function as 6t - 12. Setting this equal to zero and solving for t, we find t = 2. Therefore, the particle is at rest at 2 seconds.

The car is initially moving with a velocity of 15m/s and accelerates uniformly at a rate of 2m/s^2. The final velocity is given as 20m/s. To find the time taken, we can use the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken. Rearranging the equation, we have t = (v - u) / a. Substituting the given values, we get t = (20 - 15) / 2 = 2.5s. To find the distance travelled, we can use the equation s = ut + (1/2)at^2, where s is the distance travelled. Substituting the given values, we get s = 15(2.5) + (1/2)(2)(2.5)^2 = 43.75m. Therefore, the time taken is 2.5s and the distance travelled is 43.75m.

The speedometer in a moving car shows the instantaneous speed of the car. Instantaneous speed refers to the speed of an object at a specific moment in time. It is the rate at which an object is moving at any given instant. In this case, the speedometer provides the current speed of the car, allowing the driver to know how fast they are traveling at that exact moment.

All of the statements mentioned in the options are correct explanations for the concept of "All inertia frame of reference." Inertia frames of reference are those frames in which Newton's laws of motion hold true without the need for any additional forces or acceleration. These frames do not accelerate and are in relative motion to absolute space. Additionally, the laws of mechanics are applicable to all inertia frames of reference. Therefore, all the statements mentioned in the options are valid explanations for the concept.

The time of flight of a projectile can be calculated using the formula: time = (2 * initial velocity * sin(angle of elevation)) / acceleration due to gravity. In this case, the initial velocity is 100 m/s^2 and the angle of elevation is 60°. The acceleration due to gravity is usually taken as 9.8 m/s^2. Plugging in these values into the formula, we get: time = (2 * 100 * sin(60°)) / 9.8 = 17.32s. Therefore, the correct answer is 17.32s.

In the theory of relativity, the concept of simultaneity and the order of events can vary depending on the observer's reference frame. This means that two events that are simultaneous for one observer may not be simultaneous for another observer in a different reference frame. The time order of events can also be perceived differently by different observers. Therefore, the correct answer is "Reference frame" as it is the observer's frame of reference that determines the simultaneity and time order of events.

In uniform circular motion, the object moves at a constant speed along a circular path. While the speed remains constant, the velocity (which includes both speed and direction) changes because the direction of motion continuously changes. The acceleration is also changing because it is directed towards the center of the circle (centripetal acceleration), and displacement changes as the object moves around the circle. Thus, only speed remains constant in uniform circular motion.

The correct answer is 2.10m/s because the distance separating the events is given as 126m in the frame of the girl on the bicycle. Since the girl is riding at a constant speed, the distance covered in 60s is equal to the distance between the events. Therefore, the girl's speed is calculated by dividing the distance by the time, which gives us 126m / 60s = 2.10m/s.

The force that acts on a mass of 1g and gives it an acceleration of 1cm/s^2 is defined as 1 Dyne. This is because the Dyne is the unit of force in the CGS system of units, where 1 Dyne is equal to the force required to accelerate a mass of 1 gram by 1 centimeter per second squared.

The correct answer is Velocity vector. The derivative of the position vector with respect to time gives the velocity vector. This means that by differentiating the position vector function with respect to time, we can determine the rate of change of position, which is the velocity of the particle at any given time.

The time taken to reach the maximum height can be found by considering the vertical component of the velocity. Since the object is thrown upwards, the initial vertical velocity is positive. The time taken to reach the maximum height can be found using the formula: time = (final velocity - initial velocity) / acceleration. In this case, the initial velocity in the vertical direction is 8.0 m/s and the acceleration due to gravity is -9.8 m/s^2. Plugging these values into the formula, we get: time = (0 - 8.0) / (-9.8) = 0.82s. Therefore, the correct answer is 0.82s.