Newton's Laws Of Motion JEE L5 [Friction] | JEE Physics | JEE 2023 | Nurture | Vedantu Enthuse
Vedantu JEE Englishγ»67 minutes read
Friction is the focus of the session, exploring different types and problem-solving using Newton's laws. The session aims to establish a foundation for solving problems involving sliding objects.
Insights
- Friction can be divided into static and kinetic components, with static friction preventing motion and kinetic friction opposing relative motion between surfaces.
- Understanding the relationship between normal force, frictional force, and the angle of inclination is crucial in determining the acceleration of objects on inclined planes, highlighting the importance of vector resolution and friction in such scenarios.
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Recent questions
What is the focus of the session?
Friction
Who is the speaker of the session?
HRD of Physics for GE division
What is Vedantu's VIP promise?
Fee return if no improvement seen
How are contact forces explained?
Forces arising when surfaces are in contact
What is the role of friction in motion?
Opposing motion and adjusting to external forces
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Summary
00:00
"Friction, Newton's Laws, and Contact Forces"
- Friction is the focus of the session, exploring different types and problem-solving using Newton's laws.
- The session aims to establish a foundation for solving problems involving sliding objects.
- The audience is greeted, with a special mention of those changing display pictures and showing support.
- The speaker introduces himself as the HRD of Physics for the GE division, emphasizing his teaching experience and success stories.
- The schedule for the week includes a lecture on friction, a mental quiz, and an advanced problems session on Newton's laws.
- Vedantu's VIP promise is highlighted, offering fee return if improvement isn't seen, with impressive results showcased.
- Contact forces are explained as forces arising when two surfaces are in contact, with examples like sitting on a chair or walking on the road.
- The contact force is detailed as the resultant of all contact forces, with components of normal force and frictional force.
- The vector equation for contact force is presented, emphasizing the perpendicular and parallel components.
- Friction is discussed as having two components, normal and frictional, which are part of the same contact force, with a focus on direction determination.
17:57
Forces at Rest: Contact, Normal, Frictional
- The situation involves finding the contact force, normal force, and frictional force when the system is at rest.
- The contact force must balance the weight (mg) vertically.
- The contact force resolves into two components: one along the surface (friction) and one perpendicular to the surface (normal).
- The normal force is equal to mg cos theta, while the frictional force is mg sine theta.
- The limiting frictional force is the maximum static friction before motion begins.
- Static friction opposes the tendency of motion, adjusting to balance external forces.
- Kinetic friction remains constant once motion begins, always less than the maximum static friction.
- Frictional force direction is determined by opposing the tendency of motion for static friction and opposing the actual motion for kinetic friction.
- Friction can act in the direction of the force, opposing velocity rather than the force itself.
- Understanding the direction of friction is crucial for comprehending its role in opposing motion and adjusting to external forces.
35:57
Friction: Static vs. Kinetic Forces Explained
- When an object is at rest, static friction adjusts to external forces to keep the object stationary.
- Static friction (fs) equals the applied force (f) when acceleration is zero, up to a maximum limit called fsmax.
- Fsmax is experimentally determined to be proportional to the normal force (n), represented by the coefficient of static friction (mu s).
- The coefficient of static friction (mu s) depends on the surfaces in contact, determining the maximum friction that can be withstood.
- Kinetic friction (fk) opposes relative motion between surfaces and is constant for a given normal force and surface, represented by the coefficient of kinetic friction (mu k).
- Mu k is specific to the surfaces in contact, with higher values indicating rougher surfaces and lower values indicating smoother surfaces.
- Static friction is greater than kinetic friction, making it harder to initiate motion than to maintain it.
- The frictional force remains constant in kinetic friction, opposing motion consistently.
- In scenarios where an object is at rest or in motion, the forces acting on it can be analyzed through free body diagrams to determine the equilibrium or acceleration.
- When an object is on the verge of sliding, static friction reaches its maximum value (fsmax) before transitioning to kinetic friction.
54:57
Forces and Acceleration in Physics Problems
- Normal force is not always equal to mg, especially when there are other forces in the vertical direction.
- Friction force is not always equal to mu mg, contrary to common misconceptions.
- The correct formula for friction is mu k multiplied by the normal force, which is equal to f sine theta plus mg.
- The acceleration can be calculated using the formula f cos theta minus mu k f sine theta minus mu k mg, divided by mass.
- Normal force is equal to mg only when there are no other forces in the vertical direction.
- The resolution of vectors is necessary when dealing with forces acting at angles, as problems are typically solved in one dimension.
- The difference between fs and fx max is crucial, with fs being the value of friction at any given instant and fx max being the limiting value.
- The coefficient of friction can be experimentally determined by finding the angle of repose at which an object begins to slide on an inclined surface.
- The angle of repose is the angle at which an object is on the verge of sliding and is determined by the equation tan alpha equals mu s.
- In a system involving inclined planes, blocks, pulleys, and strings, the acceleration of the blocks can be calculated by analyzing the forces acting on each block and applying Newton's laws of motion.
01:13:26
"Physics of Braking: Calculating Speed and Friction"
- Registration for scholarships and prizes is free, with details provided in a lecture.
- A car enters a slope at 30 meters per second and 30 degrees angle, applying brakes.
- To find the speed at the bottom, vector resolution and friction's role are crucial.
- Acceleration is determined using force equations, considering deceleration due to braking.
- Kinematic equations are applied to calculate the final speed at the bottom of the slope.
- Emphasis on understanding friction's direction and its opposition to motion.
- Horizontal force needed to move a block is determined by balancing forces and considering friction.
- Friction acts at an angle to counteract the resultant force of weight and applied force.
