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Laws of Motion One Shot Physics with Live Experiments | Class 11 Physics NCERT | By Ashu Sir

Science and Fun Education・144 minutes read

The channel "Science and Fun Jahan" delves into Units and Measurements, Motion, Laws of Motion, and the importance of understanding force basics, balanced and unbalanced forces, inertia, and momentum. Discussions on Newton's laws, tension, impulse, friction, and the angle of repose demonstrate practical applications in daily life scenarios and exam preparation.

Insights

Force is the push or pull on an object, causing various effects like movement, speed, direction, and shape changes.
Balanced forces result in zero net force, while unbalanced forces are necessary for altering an object's state, shape, and size.
Newton's first law explains objects' tendency to remain at rest or in motion unless acted upon by external forces, demonstrated in daily scenarios like bus rides.
Newton's second law establishes the relationship between force, momentum, and acceleration, with practical applications in daily activities like catching a ball or using seat belts.

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Recent questions

What is the definition of force?
Force is a push or pull on an object.
What are Newton's laws of motion?
Newton's laws describe motion and force.
How does inertia affect objects?
Inertia resists changes in an object's state.
What is the Law of Conservation of Momentum?
Momentum remains constant before and after collisions.
What is the role of friction in physics?
Friction opposes motion between objects.

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Summary

00:00

Understanding Forces and Laws of Motion

The channel "Science and Fun Jahan" discusses Units and Measurements, Motion in a Sketch Line, Motion in a Plane, and Laws of Motion.
The channel conducts experiments to demonstrate concepts like Motion in a Plane and Laws of Motion.
The channel emphasizes the importance of understanding the basics of force and the laws of motion.
The channel explains that force is the push or pull on an object, irrespective of the effect it produces.
Force can move a stationary object, stop a moving object, change speed, direction, and shape and size.
There are two types of forces: balanced and unbalanced forces.
Balanced forces result in a net force of zero on an object, while unbalanced forces lead to a non-zero net force.
Unbalanced forces are necessary to change the state, shape, and size of an object.
Unbalanced forces can cause significant changes, such as altering the shape of objects in collisions.
Balanced forces, on the other hand, primarily focus on changing the shape of objects.

13:27

Newton's First Law: Inertia in Motion

Unbalanced force is caused by changing the shape and size, not by applying balance force.
Newton's first law states that objects at rest remain at rest unless an external force is applied.
Objects in motion continue in motion in a straight line with the same speed unless an external force is applied.
Inertia is the tendency of objects to remain in their state of rest or motion unless acted upon by an external force.
Demonstrations of Newton's first law include experiments with potatoes, eggs, and water-filled containers.
The application of Newton's first law is seen in daily life scenarios like falling backward in a moving bus or stopping suddenly.
The upper body wants to remain at rest while the lower body is in motion, causing the sensation of falling backward in a moving bus.
Wet clothes stick together due to water's inertia, requiring force to separate them.
Stacked coins remain in place when the bottom coin is hit, demonstrating inertia.
Seat belts and airbags in cars prevent passengers from moving forward during sudden stops, following Newton's first law.

26:37

Newton's Second Law: Force and Acceleration

When a hammer is hit against a wall, it turns upside down and hits the wall, causing the head to sink inward.
The rod and head of the hammer are in motion and collide like walls, with the handle coming to rest while the head wants to remain in motion.
Inertia, a property of substances, prevents changes in their state, with mass directly proportional to inertia.
Inertia of rest, motion, and direction dictate how objects resist changes in their state.
Momentum is the product of mass and velocity, representing the impact of collision based on these factors.
Momentum is a vector quantity, with direction aligned with velocity, and its unit is kg meter per second.
Newton's second law states that force is directly proportional to the rate of change of momentum, emphasizing the importance of applying force to alter momentum.
The formula for force is mass multiplied by acceleration, with the constant value typically being one.
The new formula derived from Newton's second law is force equals mass times acceleration, simplifying the relationship between force and acceleration.
Understanding Newton's second law involves recognizing the relationship between force and acceleration, providing a fundamental formula for calculating force.

41:50

Newton's Laws: Force, Momentum, and Reactions

The speaker had invited someone who declined due to work commitments, potentially leading to a missed opportunity.
Mention of Newton's second law, explaining the relationship between force, momentum, and time.
Emphasis on force being directly proportional to the change in momentum over time.
Practical application of Newton's second law in daily life scenarios, like catching a ball or avoiding glass breakage.
Explanation of how wicket keepers in cricket move their hands back to reduce force impact.
Detailed example of glass falling on different surfaces to illustrate force and momentum changes.
Application of Newton's second law in long jump scenarios, using mattresses to reduce force impact.
Explanation of how seat belts work based on Newton's second law to prevent sudden momentum changes.
Discussion of Newton's third law, stating that every action has an equal and opposite reaction.
Practical demonstrations with a balloon and a lighter to showcase Newton's third law in action.

56:05

Newton's Laws and Momentum in Motion

Understanding the concept of action and reaction, focusing on Newton's Third Law and its applications.
Explaining the principle of rockets and boats moving forward based on equal and opposite reactions.
Differentiating between manual boats and motor boats, with motor boats propelled by a water motor at the back.
Detailing the science behind the movement of boats and the impact of mass and acceleration on their motion.
Introducing the Law of Conservation of Momentum, emphasizing the importance of total momentum before and after collisions.
Describing the formula for momentum as mass multiplied by velocity and its application in understanding collisions.
Demonstrating the proof of the Law of Conservation of Momentum using Newton's Second and Third Laws.
Exploring the concept of tension in objects, illustrating how tension balances forces to prevent movement.
Discussing the scenario of a fan attached to a rod and how tension in the string prevents the fan from falling.
Engaging in a thought experiment regarding the breaking of strings under different forces, highlighting the impact of tension on string strength.

01:11:07

Physics of Lifts: Weight and Acceleration

An object with 250 Newtons will break first due to tension.
Understanding the concept of normal reaction is crucial in physics.
Normal reaction is also known as apparent weight, felt when standing on a surface.
The normal reaction is always perpendicular to the surface.
In lift cases, different scenarios affect how we feel weight in elevators.
In a lift at rest, the apparent weight equals the actual weight.
When the lift moves up or down at a uniform velocity, the weight remains constant.
Acceleration in lift cases can make us feel lighter or heavier.
Free fall in a lift results in weightlessness due to acceleration equal to gravity.
An interesting case involves acceleration greater than gravity, affecting weight in a lift.

01:29:09

"Downward Acceleration, Tension, and Impulse Explained"

Acceleration is greater than G when moving downwards
Formula for net force is mass into acceleration
Negative r means weight will start moving upwards
Weight will stick to the ceiling if the lift doesn't have a roof
Demonstrated using a jar as an elevator with a paper ball inside
Explained connected motion with two masses connected by a thread over a pulley
Derivation of acceleration formula for connected motion: g(m1 - m2) / (m1 + m2)
Tension formula derived: 2m1m2g / (m1 + m2)
Importance of knowing tension and acceleration for designing lifts or cranes
Impulse defined as force applied for a very short period of time, measured in Newton seconds

01:45:27

Impulse Momentum Theorem: Key Concepts Explained

The theorem was expanded to include impulse momentum, also known as theorem I.
Impulse is equivalent to change in momentum, as per the theorem.
Impulse formula is derived from Newton's second law, relating force to change in momentum over time.
The Impulse Momentum Theorem states that impulse equals momentum change.
The theorem's significance is highlighted in NCERT and NEET exams.
Impulse has gained importance in exams, with numerous questions arising.
The SI unit for impulse is kilogram meter per second.
Friction is defined as a force opposing motion between objects in contact.
Friction occurs not only when objects are in motion but also when they resist motion.
Friction arises from interlocking irregular surfaces or weak Wonderwall forces of attraction between particles.

02:01:20

Understanding Friction and its Characteristics

Friction is also known as static friction and self-adjusting friction.
Static friction adjusts according to the force applied.
There is a limit to the force that can be applied before the object starts moving.
The maximum value of static friction is called limiting friction.
Limiting friction is the maximum value of static friction.
Kinetic friction occurs when an object starts moving.
Kinetic friction is always slightly less than limiting friction.
Frictional force depends on the normal reaction and the nature of the material.
Friction is directly proportional to the normal reaction.
The angle of friction is the angle between the normal reaction and the resultant of friction.

02:17:09

Material Determines Speed: Angle of Repose Key

The speed at which an object falls depends on the material it is made of, with rubber being rough and glass being smooth.
When comparing two glasses on an inclined plane, the angle of repose is crucial in determining which glass will slide faster.
The angle of repose is the same for objects of the same material, regardless of weight.
The angle of repose is determined by the balance between downward force and frictional force.
The angle of repose is mathematically derived from the components of gravitational force acting on an inclined plane.
The angle of repose is solely dependent on the material of the object, not its weight.
The angle of repose is equal to the angle of friction, although they are conceptually different.
The maximum velocity without skidding during a turn is determined by the balance between centripetal force and friction.
The maximum velocity without skidding is calculated as the square root of the product of mass, acceleration due to gravity, and radius of the turn.
Increasing velocity without skidding is limited by the friction available, with excessive speed leading to slipping.

02:32:01

Banking Off Road: Friction and Velocity Formula

The video discusses the concept of banking off road, where roads are lifted on one side when taking a turn.
Friction plays a crucial role in this concept, always acting towards the center.
The normal reaction is upward, while the friction force is towards the bottom.
The derivation of the banking off road concept is highlighted as the most important part of the chapter.
The formula for maximum velocity without skidding is derived, emphasizing the importance of finding the value of 'r' first.
Optimum speed on a flat road without friction is discussed, where velocity becomes zero without friction.
The formula for maximum velocity without skidding on a banked road is detailed, showing the impact of friction on turning safely.

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