Motion, laws of motion

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<–2/”>a >Motion

Motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance, velocity, acceleration, time and speed.

The branch of physics which deals with the study of motion of material objects is called mechanics.

Mechanics is divided into following branches.

(i) Statics : Statics is the branch of mechanics which deals with the study of motion of objects under the effect of forces in equilibrium.

(ii) Kinematics :

It is that branch of mechanics which deals with the study of motion of object without taking into account the factors (i.e. nature of forces, nature of bodies etc.) which cause motion. Here time factor plays an essential role.

(iii) Dynamics :

It is that branch of mechanics which deals with the study of motion of objects taking into account the factors whichcause motion.

Rest : An object is said to be at rest if it does not change its position with time, with respect to its surroudings.

A book lying on a table, a person sitting in a chair are the examples of rest.

Motion : An object is said to be in motion if it changes its position with time, with respect to its surroundings.

Example : A bird flying in air, a train moving on rails, a ship sailing on water, a man walking on road are some of the examples of motion, visible to the eye. Motion of gas Molecules is an example of motion, invisible to the eye.

Rest & Motion are relative terms :

When we say that an object is at rest or in motion,then this statement is incomplete and meaningless. Basically, rest & motion are relative terms. An object which is at rest can also be in motion simultaneously. This can be illustrated as follows.

The passengers sitting in a moving bus are at rest with respect to each other but they are also in motion at the same time with respect to the objects like trees, buildings on the road side. So the motion and rest are relative terms.

Rectilinear motion :

If a particle moves in a fixed direction, the motion of this type is called rectilinear motion or one dimensional motion.For example the motion of an ant on a wire is a rectilinear motion.

Two dimensional motion :

If the motion of a particle is in such a way that its position remains on a fixed plane, then the motion of a particle is called two dimensional motion.

Laws Of Motion

 

 

First Law of Motion

A body continue to be in its state of rest or of uniform motion along a straight line, unless it is acted upon by some external force to change the state

(1) If no net force acts on a body, then the velocity of the body cannot change i.e. the body cannot accelerate.

(2) Newton‟s first law defines inertia and is rightly called the law of inertia. Inertia are of three types :Inertia of rest, Inertia of motion, Inertia of direction

(3) Inertia of rest : It is the inability of a body to change by itself, its state of rest. This means a body atrest remains at rest and cannot start moving by its own.

Second Law of Motion

(1) The rate of change of linear momentum of a body is directly proportional to the external force appliedon the body and this change takes place always in the direction of the applied force.

(2) If a body of mass m, moves with velocity v then its linear momentum can be given by p= mv and if force is applied on a body, then Force = mass ? acceleration

Third Law of Motion

To every action, there is always an equal (in magnitude) and opposite (in direction) reaction.

(1) When a body exerts a force on any other body, the second body also exerts an equal and opposite forceon the first.

(2) Forces in nature always occurs in pairs. A single isolated force is not possible.

(3) Any agent, applying a force also experiences a force of equal magnitude but in opposite direction. Theforce applied by the agent is called „Action‟ and the counter force experienced by it is called „Reaction‟.

(4) Action and reaction never act on the same body. If it were so the total force on a body would have always been zero i.e. the body will always remain in equilibrium.

(5) If F (AB)= force exerted on body A by body B (Action) and F(BA)= force exerted on body B by body A (Reaction) Then according to Newton‟s third law of motion F (AB) = F(BA)

(6) Example : (i) A book lying on a table exerts a force on the table which is equal to the weight of the book. This is the force of action.,

Motion is the change in position of an object over time. It can be described in terms of its speed, velocity, and acceleration.

Speed is the rate at which an object changes its position. It is measured in meters per second (m/s).

Velocity is the rate at which an object changes its position and direction. It is measured in meters per second squared (m/s^2).

Acceleration is the rate at which an object’s velocity changes. It is measured in meters per second squared (m/s^2).

There are three laws of motion that describe how objects move. These laws were first proposed by Isaac Newton in the 17th century.

Newton’s first law of motion states that an object will remain at rest or in uniform motion unless acted upon by an unbalanced force. This means that if an object is not moving, it will not start moving unless something pushes or pulls on it. And if an object is moving, it will keep moving in the same direction and at the same speed unless something pushes or pulls on it.

Newton’s second law of motion states that the acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass. This means that the harder you push on an object, the faster it will accelerate. And the more massive an object is, the harder it will be to accelerate.

Newton’s third law of motion states that for every action, there is an equal and opposite reaction. This means that when you push on something, it pushes back on you with the same amount of force.

There are many different types of motion. Some common types of motion include:

  • Acceleration: This is the rate at which an object’s speed changes.
  • Angular acceleration: This is the rate at which an object’s angular velocity changes.
  • Angular momentum: This is the product of an object’s mass, its radius, and its angular velocity.
  • Average speed: This is the total distance traveled divided by the total time taken to travel that distance.
  • Centripetal force: This is the force that keeps an object moving in a circular path.
  • Circular motion: This is the motion of an object in a circle.
  • Constant speed: This is the motion of an object at a constant speed.
  • Distance: This is the length of the path traveled by an object.
  • Displacement: This is the change in the position of an object.
  • Force: This is any interaction that changes the motion of an object.
  • Free fall: This is the motion of an object under the influence of gravity only.
  • Friction: This is the force that opposes the relative motion of two surfaces in contact.
  • Gravity: This is the force of attraction between two objects with mass.
  • Inertia: This is the tendency of an object to resist changes in its motion.
  • Kinetic energy: This is the energy of motion.
  • Linear momentum: This is the product of an object’s mass and its velocity.
  • Mass: This is a measure of the amount of matter in an object.
  • Newton’s first law of motion: This law states that an object will remain at rest or in uniform motion unless acted upon by an unbalanced force.
  • Newton’s second law of motion: This law states that the acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass.
  • Newton’s third law of motion: This law states that for every action, there is an equal and opposite reaction.
  • Orbital motion: This is the motion of an object around another object.
  • Projectile motion: This is the motion of an object that is thrown or projected into the air.
  • Speed: This is the rate at which an object changes its position.
  • Uniform motion: This is the motion of an object at a constant speed.
  • Velocity: This is the rate at which an object changes its position and direction.
  • Weight: This is the force of gravity on an object.

Motion is a fundamental property of the universe. It is the basis of all change and all activity. Without motion, there would be no life, no change, and no progress.

1. What is the difference between speed and velocity?

Speed is a measure of how fast an object is moving, while velocity is a measure of how fast an object is moving and in what direction.

2. What is the difference between acceleration and deceleration?

Acceleration is the rate at which an object’s speed changes, while deceleration is the rate at which an object’s speed decreases.

3. What is the difference between force and mass?

Force is a push or pull that causes an object to change its motion, while mass is the amount of matter in an object.

4. What is the difference between weight and mass?

Weight is the force of gravity on an object, while mass is the amount of matter in an object.

5. What is the difference between inertia and momentum?

Inertia is the tendency of an object to resist changes in its motion, while momentum is the product of an object’s mass and velocity.

6. What is the difference between friction and air resistance?

Friction is a force that opposes the relative motion of two surfaces that are in contact, while air resistance is a force that opposes the motion of an object through the air.

7. What is the difference between work and energy?

Work is the transfer of energy from one object to another, while energy is the ability to do work.

8. What is the difference between potential energy and kinetic energy?

Potential energy is energy that is stored due to the position or arrangement of an object, while kinetic energy is energy that is due to an object’s motion.

9. What is the difference between power and force?

Power is the rate at which work is done, while force is a push or pull that causes an object to change its motion.

10. What is the difference between torque and angular momentum?

Torque is a force that causes an object to rotate, while angular momentum is the product of an object’s mass, radius, and angular velocity.

11. What is the difference between centripetal force and centrifugal force?

Centripetal force is a force that acts towards the center of a circular path, while centrifugal force is an apparent force that acts away from the center of a circular path.

12. What is the difference between static equilibrium and dynamic equilibrium?

Static equilibrium is a state of balance in which an object is not moving, while dynamic equilibrium is a state of balance in which an object is moving at a constant speed.

13. What is the difference between projectile motion and uniform circular motion?

Projectile motion is the motion of an object that is thrown or projected into the air, while uniform circular motion is the motion of an object that is moving in a circle at a constant speed.

14. What is the difference between simple harmonic motion and periodic motion?

Simple harmonic motion is a type of periodic motion in which an object moves back and forth between two positions, while periodic motion is any motion that repeats itself over and over again.

15. What is the difference between wave motion and particle motion?

Wave motion is the motion of a disturbance that travels through a medium, while particle motion is the motion of individual particles.

Sure, here are some multiple choice questions about motion and the laws of motion:

  1. Which of the following is not a type of motion?
    (A) Acceleration
    (B) Deceleration
    (C) Speed
    (D) Velocity

  2. Which of the following is the correct equation for calculating acceleration?
    (A) $a = \frac{v_f – v_i}{t}$
    (B) $a = \frac{v_i + v_f}{2}$
    (C) $a = \frac{v_f^2 – v_i^2}{2t}$
    (D) $a = \frac{v_i^2 – v_f^2}{2t}$

  3. Which of the following is the correct equation for calculating velocity?
    (A) $v = \frac{d}{t}$
    (B) $v = at$
    (C) $v = \sqrt{v_f^2 – v_i^2}$
    (D) $v = \frac{v_f + v_i}{2}$

  4. Which of the following is the correct equation for calculating displacement?
    (A) $d = vt$
    (B) $d = at^2$
    (C) $d = \sqrt{v_f^2 – v_i^2}$
    (D) $d = \frac{v_f + v_i}{2}$

  5. Which of the following is the correct equation for calculating time?
    (A) $t = \frac{d}{v}$
    (B) $t = \frac{v}{a}$
    (C) $t = \sqrt{\frac{v_f^2 – v_i^2}{2a}}$
    (D) $t = \frac{v_f + v_i}{2}$

  6. Which of the following is the first law of motion?
    (A) An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
    (B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
    (C) For every action, there is an equal and opposite reaction.

  7. Which of the following is the second law of motion?
    (A) An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
    (B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
    (C) For every action, there is an equal and opposite reaction.

  8. Which of the following is the third law of motion?
    (A) An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
    (B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
    (C) For every action, there is an equal and opposite reaction.

  9. Which of the following is not an example of a force?
    (A) Gravity
    (B) Friction
    (C) Air resistance
    (D) Speed

  10. Which of the following is not an example of an unbalanced force?
    (A) The force of gravity on a falling object
    (B) The force of friction between a moving object and the surface it is moving on
    (C) The force of air resistance on a moving object
    (D) The force of a person pushing on a cart

I hope these questions were helpful! Let me know if you have any other questions.