The motion of a particle of mass m is described by the relation, y = ut - 1⁄2 gt2, where u is the initial velocity of the particle. The force acting on the particle is

The correct answer is F = - mg.

Key Points

• The motion of a particle of mass m is described by the relation, y = ut - 1⁄2 gt2, where u is the initial velocity of the particle.
• The force acting on the particle is given by:
  • F = - mg

Additional Information

• ​Newton’s Laws of Motion:
  • According to the first law of motion, "An object at rest will remain at rest and an object moving with uniform velocity will continue to continue with uniform velocity unless we apply an external force on it."
    • For example, a car moving with some velocity will continue to move until we apply brakes to stop it. A ball kept on the road will remain at rest unless we apply some force to move it.
  • According to Newton's second law of motion, "The rate of change of momentum of any object is directly proportional to the direction of the force applied on the object."
  • Newton's third law of motion states that: "For every action there is always an equal and opposite reaction".