Samacheer Class 6 Science - Force and Motion

The first statement is true because to and fro motion, where an object moves back and forth along the same path repeatedly, is indeed called oscillatory motion. The second statement is true because vibratory motion, which involves rapid back and forth movements, and rotatory motion, which involves spinning around an axis, are both examples of periodic motions that repeat at regular intervals. The third statement is non-uniform motion because vehicles moving with varying speeds do not travel equal distances in equal intervals of time, which is the definition of uniform motion. The fourth statement is false because robots are machines programmed to perform specific tasks automatically, but they operate based on programmed instructions and cannot develop consciousness or independent thought like humans do. Robots will continue to assist and automate many tasks in the future, but they cannot replace human consciousness, creativity, and decision-making abilities.

A non-contact force is a force that acts on an object without requiring any physical contact between the object and the source of the force. Examples of non-contact forces include gravitational force, which pulls objects toward the Earth without touching them, magnetic force, which attracts or repels magnetic materials from a distance, and electrostatic force, which acts between charged objects without them touching each other. These forces operate through fields that extend through space around the source.

Motion is a change in the position of an object with respect to time and a reference point. When an object moves from one location to another, or when its distance from a fixed reference point changes over time, the object is said to be in motion. Motion can occur in different directions and at different speeds, and it is relative, meaning whether an object is in motion or at rest depends on the observer's frame of reference.

Oscillatory motion is the motion of an object that repeats itself after a fixed interval of time, moving back and forth along the same path. In oscillatory motion, the object returns to its starting position after completing one full cycle. Common examples include the swinging of a pendulum, the vibration of a tuning fork, and the motion of a child on a swing. The time taken to complete one full cycle is called the period of oscillation.

Uniform motion is the motion of an object that travels equal distances in equal intervals of time. In uniform motion, the speed of the object remains constant throughout its journey, meaning the object covers the same amount of distance in every unit of time. For example, if a car travels 60 kilometers in one hour, and continues to travel 60 kilometers in every subsequent hour, it is said to be in uniform motion. The velocity remains constant in uniform motion, and the object moves in a straight line without any change in speed or direction.

A robot is a machine capable of carrying out a complex series of actions automatically, either independently or under the control of a human operator. Robots are programmed to perform specific tasks with precision and consistency. They can be designed for various purposes such as manufacturing, exploration, medical assistance, or household work. Robots operate based on programmed instructions and sensors that allow them to interact with their environment and complete assigned tasks efficiently.

Force is defined as a push or pull exerted by an animate or inanimate agency on an object. A push or pull can change the state of motion of an object, change its direction, or change its shape. Forces can be classified into two main categories: contact forces, which require physical contact between the object and the source of force such as friction and applied force, and non-contact forces, which act without physical contact such as gravitational force and magnetic force. Force is a vector quantity, meaning it has both magnitude and direction.

Different types of motion can be classified based on the path followed by an object. Linear motion occurs when an object moves in a straight line, such as a car moving on a straight road. Curvilinear motion occurs when an object moves along a curved path, such as a ball thrown at an angle. Circular motion occurs when an object moves along a circular path, such as a planet orbiting the sun. Rotatory motion occurs when an object spins or rotates about a fixed axis, such as the rotation of a spinning top or the Earth rotating on its axis. Oscillatory motion occurs when an object moves back and forth repeatedly along the same path, such as a pendulum swinging. Zigzag or irregular motion occurs when an object moves in an unpredictable pattern without following a regular path, such as a mosquito flying randomly in a room.

If you are sitting in a moving car, you are at rest with respect to your friend sitting next to you inside the car. This is because both you and your friend are moving together at the same velocity relative to the ground. Since you are both moving at the same speed and in the same direction, there is no change in the distance between you and your friend. Motion is relative, meaning it depends on the frame of reference chosen. With respect to your friend inside the car, you are stationary. However, with respect to a person standing outside the car on the road, both you and your friend are in motion because your positions are changing relative to that stationary observer.

Average speed = \(\frac{distence}{time}\)
= \(\frac{400}{5}\) = 80 km per hour

Forces are classified into two main types based on the nature of their application. Contact forces are those that require direct physical contact between two objects to produce an effect, such as pushing, pulling, or friction. Non-contact forces are those that can act on an object without any direct physical contact, such as gravitational force, magnetic force, and electrostatic force. These two categories encompass all types of forces that can act on objects in the physical world.

On the basis of contact, forces are classified into two main types. Contact forces are forces that act when two objects are in direct physical contact with each other, such as when you kick a ball or push a door. Non-contact forces are forces that can act on an object from a distance without any direct physical contact between the objects, such as gravitational force between the Earth and objects, magnetic force between magnets, and electrostatic force between charged objects. These two categories represent the fundamental ways in which forces can be applied to objects.

Non-periodic motion is a type of motion in which the moving object does not repeat its path or motion at regular or uniform intervals of time. In non-periodic motion, the time intervals between successive occurrences of the same motion are not equal or constant. This means the motion does not follow a predictable pattern that repeats itself. Examples of non-periodic motion include the random movement of dust particles in air, the irregular bouncing of a ball on an uneven surface, or the unpredictable motion of leaves falling from a tree. Non-periodic motion is characterized by its lack of regularity and predictability, unlike periodic motion which repeats at fixed time intervals.