Motion is a phenomenon through which a body changes its location over time. It is mathematically expressed in terms of displacement, distance, speed, velocity, time and acceleration. The movement of a body is analysed by fixing a reference frame to the observer and calculating the change in location of the body with respect to the frame with variation in time.
Physical systems are connected to motion: matter particles, radiation, matter fields, radiation, and space-time. In general, motion signifies a continuous variation in the configuration or positions of a physical body in space. Newton’s laws of motion describe the connection between forces exerting on a system and its motion. These laws are the basic principles that control classical mechanics. The Aristotelian theory was the widely accepted theory about motion in the Western world. His theory described the motion as follows: In the absence of outside power, all bodies would come to a stationary state (rest) where moving bodies stay only to move until force or power is inducing the bodies to do so. Even though it was widely accepted, this motion theory was opposed by many notable scholars.
Later, Galileo Galilei further developed the theory of inertia. He hypothesised that a falling body acquires an equal value of velocity in equal time intervals. This implies that the speed rises at a constant figure as it descends. However, there was a major problem in testing this theorem: It was not possible for him to observe the free-falling movement of the body. Also, the technology was too underdeveloped to record such extreme velocities. If a body is released from the state of rest and acquires speed at a consistent rate, then the entire distance covered by the body is proportional to the time squared required for that travel.
In classical mechanics, there is no clear distinction between consistent motion in a straight path. They can be regarded as the exact state of motion perceived by different persons, one travelling at the exact velocity of the body and the other travelling at a steady velocity relative to the body. This is called the law of inertia. It was first developed by Galileo Galilei for horizontal movement on the Earth. It was later generalised by René Descartes. Even though the law of inertia is the beginning point and the basic foundation of classical mechanics, it is not very intuitive to the untrained observer.
In Aristotelian conception and in normal experience, bodies that are not being thrust tend to approach the state of rest. The principle of inertia was developed by Galileo from his experiments with rolling balls with inclined planes. Inertia is the property of an object through which it resists any change in the nature of motion or state of rest. Inertia is a passive character and does not allow an object to indulge in anything except resist active agents like torques and forces. A moving object stays moving not due to its inertia. It is only due to the lack of force to damp it down, vary its trajectory, or speed it up.
The video explains the basic concept of motion
Important Law of Inertia Questions with Answers
1) What is motion?
Motion is a phenomenon through which a body changes its location over time. It is mathematically expressed in terms of displacement, distance, speed, velocity, time and acceleration.
2) The branch that deals with the motion of bodies without concerning its cause is called ______.
Answer: kinematics
Explanation: The branch that deals with the motion of bodies without concerning its cause is called kinematics.
3) The branch that examines forces and their impacts on motion is called ______.
Answer: dynamics
Explanation: The branch that examines forces and their impacts on motion is called dynamics.
4) Why is it impossible to determine absolute motion?
Suppose a body is not changing with respect to a given reference frame. In that case, the body is considered to be at rest, immobile, stationary, or possesses a time-invariant or constant position with respect to its surroundings. Since there is no absolute reference frame, it is not possible to determine the absolute motion. Thus, everything in this cosmos can be regarded to be in motion.
5) What is inertia?
Inertia is the property of an object through which it resists any change in the nature of motion or state of rest. Inertia is a passive character and does not allow an object to indulge in anything except resist active agents like torques and forces. A moving object stays moving not due to its inertia. It is only due to the lack of force to damp it down, vary its trajectory, or speed it up.
6) Who developed the theory of inertia?
Galileo Galilei developed the theory of inertia. He hypothesised that a falling body acquires an equal value of velocity in equal time intervals. This implies that the speed rises at a constant figure as it descends.
7) How did Galileo measure the speed of the falling object?
In order to counter the technological disadvantage he had, Galileo tried to slow down the body’s motion by replacing the descending body with a ball rolling along an inclined plane. As free-falling motion is fundamentally equivalent to a fully vertical ramp, Galileo thought that a ball rolling along a ramp would accelerate in the exact way as a descending ball would. Using a water clock, he calculated the time consumed for the ball to reach a particular distance down the slanted plane. After many trials, he observed that the time consumed by the ball to roll the complete length of the ramp was equivalent to double the time consumed by the same ball to roll a quarter of the length. Through the test, he concluded that if a body is once in a state of motion, it moves with a uniform velocity if no external force acts on it.
8) Define Newton’s first law of motion.
Newton’s first law of motion states if an object is at the state of rest or in motion at a constant rate in a straight line, it will stay at rest or continue moving in a straight path at sustained speed unless it is disturbed by an external force.
9) What are the two quantitative measures of the inertia of an object?
There are fundamentally two quantitative measures of the inertia of an object: mass and moment of inertia. Mass control its resistance to the exertion of a force on the object. Moment of inertia along a particular axis measures the object’s resistance to the exertion of torque along the same axis. In general usage, inertia may refer to a body’s measure of resistance to change in speed or velocity. In simple terms, it is the opposition to a change in the state of motion (sometimes to the body’s momentum).
The law of inertia is one of the basic principles in classical mechanics that are still employed to explain the motion of bodies and how they are impacted by the applied forces on them.
10) What misled Aristotle to conclude that bodies would be in motion only if continuous force was exerted on them?
On the Earth’s surface, inertia is usually masked by the force of gravity and the impacts of air resistance and friction, both of which tend to reduce the speed of moving bodies (typically to the state of rest).
11) What are the main types of inertia?
The inertia of direction, the inertia of rest, and the inertia of motion are the main types of inertia.
12) What is meant by the inertia of rest?
A body continues to stay where it is positioned, and it will continue to be there until an external force moves it.
13) What is meant by the inertia of motion?
A body will continue to move at the same velocity until an external force is applied to it. For example, an object in a moving car going forward when the car stops suddenly.
14) What is meant by the inertia of direction?
A body will continue to move in the same direction until an outside force is applied to it.
15) Explain some common scenarios of inertia of rest.
When a vehicle is suddenly accelerated, passengers might feel as though they are moving backwards. Inertia forces the passengers to continue in place as the vehicle travels forward.
If a stationary vehicle is collided with a moving vehicle from behind, the driver may experience whiplash. This is the result of the driver’s body travelling in the forward direction but the driver’s head lagging behind. Here, the inertia is experienced by the head.
A balloon in a vehicle will seem to move when the vehicle travels forward. However, in reality, the balloon is trying to stay in the position it was in earlier. It is only the vehicle that is moving forward.
A table cloth can be taken out from underneath the plates and utensils if it is pulled quickly. The plates and utensils have the inherent tendency to stay still as long as the motion of the tablecloth is not too overpowering.
|
Related Topics |
|---|
Practice Questions
1) What is Aristotle’s fallacy?
2) Explain Galileo’s fall experiment.
3) Give one scenario where the law of inertia is proven.
4) Which Newton’s law is connected to the law of inertia?
5) Which type of clock was used by Galileo to measure the time during the fall experiment?
Stay tuned to BYJU’S and Fall in Love with Learning!
