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National Bird Day: Why Birds Matter to Us

National Bird Day is celebrated every year on 5 January . This day is observed to spread awareness about birds, their importance in nature, and the need to protect them. Birds are beautiful living beings and play a very important role in keeping our environment healthy. Origin of National Bird Day National Bird Day was first celebrated in the year 2002 . It was started by bird lovers and environmental groups to protect birds from dangers like deforestation, pollution, and illegal hunting. The main aim of this day is to teach people, especially students, why birds are important and how we can help save them. Why Is National Bird Day Celebrated Every Year? National Bird Day is celebrated every year because many bird species are disappearing due to human activities. Cutting trees, using plastic, pollution, and climate change are harming birds and their homes. This day reminds us that: Birds need protection Nature should be respected Everyone has a responsibil...
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Newton’s second law | Mechanics

Newton’s second law 

  • According to this law the rate of change of momentum is directly proportional to the applied force, and the change in momentum is always takes place in the direction of applied force.
  • F ∝ (dp / dt)    ⇒    F = k (dp / dt)
  • Here F is applied force, p is linear momentum and k is constant of proportionality.
  • In S.I. k = 1
  • ∴   F = dp / dt
  • ∵   p = mv
  • ∴   F = d(mv) / dt    ⇒    F = m (dv / dt)    ⇒    F = ma    (∵ a = dv / dt)
  • Thus Newton’s second law gives the quantitative definition of force.
  • If ax, ay and az are the components of acceleration in x, y and z directions respectively, then
  • F = m (ax i + ay j + az k) = (max) i + (may) j + (maz) k
  • F = Fx i + Fy j + Fz k
  • Since Newton’s first and third laws can be derived from second law, and hence this law is the real law of motion or the most fundamental law of motion.
  • ∵     a = F / m
  • ∴     Acceleration ∝ 1 / Mass
  • It means greater is the mass of the body, smaller is the acceleration produced by it.
  • Since mass is the measure of inertia of the body, therefore the mass given by above equation is known as inertial mass.
  • Acceleration produced in the body depends only on its mass, not on the initial or final velocity.

Unit of force

  • Unit of force = Unit of mass × Unit of acceleration
                               = kg  ×  m/s2 = N (newton)
  • CGS unit of force is dyne
  • 1 N = 105 dyne

Dimensional formula

  • Dimension formula of force is [MLT-2]

Accelerated motion

  • If in a motion, only the magnitude of velocity of the body changes, then in this type of motion the force is applied either along the direction of motion or opposite to the direction of motion.
  • If only the direction of the motion of the body changes, then in this type of motion the force is always applied at right angles to the direction of motion of the body. Circular motion is the example of this type of motion.

To know more about Newton's second law of motion please click on https://youtu.be/ePtqiWUZEu0
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