Patterns of problems
8 min read

Laws Of Motion

- Let's decode the pattern of problems
1
Pattern: Problem involving forces and its effect when applied at some angle.
Description: Force, in mechanics is any action that tends to maintain or alter the motion of a body or to distort it.

Question can be asked
  1. To calculate force and thrust.
  2. To calculate the net effect of force applied at some angle.
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2
Pattern: Problem based on the calculation of tension in string or rope and spring forces generated by spring.
Description: Tension and spring force are beneficiary to understand the concept of transfer of force between the bodies.

Question can be asked
  1. To calculate tension in massless string or rope.
  2. To calculate spring force.
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3
Pattern: Problem based on conservation of momentum
Description: Conservation of momentum is mostly used for describing collisions between objects and to calculate impulse and forces.

Question can be asked
  1. To calculate the velocities of bodies before/after the collision.
  2. To calculate the impulse.
  3. To calculate the change in momentum.
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4
Pattern: Problem based on constrained motion and pseudo force.
Description: Constrained motion results when an object is forced to move in a restricted way while Pseudo force comes in effect when the frame of reference has started acceleration compared to a non-accelerating frame.

Question can be asked
  1. On motion of objects with respect to frames accelerated in one dimension.
  2. On the motion of object having pseudo force applied.
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5
Pattern: Problems on friction.
Description: Friction is the resistance to motion of one object moving relative to another. It is not a fundamental force.

Question can be asked
  1. To find static friction, kinetic friction or limiting friction depending upon the situation.
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6
Pattern: Problems on circular motion and motion of car on circular road.
Description: In such type of problem, banking condition for vehicle is found based on the friction coefficient of road and the curvature of road.

Question can be asked
  1. To describe and calculate maximum velocity of the motion of car on plane road.
  2. To solve problems on cars moving on circular banked roads with friction acting on tyres.
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7
Pattern: Problem based on the applications of Newton's Second Law
Description: The second law states that the force on an object is equal to its mass times its acceleration. Problems to determine the dynamics of motion of a system can be asked. While some questions are straightforward where second law equation can be directly applied, complex systems where we need to draw free body diagram to apply the second law equation are also asked often.

Question that can be asked
  1. To solve problem related to the motion of object under constant force.
  2. To calculate the velocities and acceleration of masses in a pulley-mass system.
  3. On the motion of objects on fixed or moving wedge.
  4. On the motion of objects under variable force.
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8
Pattern: Problems based on conservation of momentum
Description: Conservation of momentum states that the total momentum of a system of interacting objects remains conserved, if no other external forces act on it.

Questions that can be asked:
  1. Problems related to rocket propulsion( based on conservation of momentum).
  2. Problems based on recoil of a gun.
Sample problems:
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