Question:

A particle of mass 100 g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time the particle goes up is :

Updated On: Jul 5, 2022
  • -0.5 J
  • -1.25 J
  • 1.25 J
  • 0.5 J
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The Correct Option is B

Solution and Explanation

The height (h)traversed by particle while going up is $h=\frac{u^{2}}{2 g}=\frac{25}{2 \times9.8}$ Work done by gravity force =$m \vec{g}. \vec{h}$ $=0.1\times g\times\frac{25}{2\times9.8} cos\, 180^{\circ}$ [Angle between force and displacement is 180?] $\therefore\, \quad W=0.1 \times\frac{25}{2}=1.25 J$
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Concepts Used:

Work

Work is the product of the component of the force in the direction of the displacement and the magnitude of this displacement.

Work Formula:

W = Force × Distance

Where,

Work (W) is equal to the force (f) time the distance.

Work Equations:

W = F d Cos θ

Where,

 W = Amount of work, F = Vector of force, D = Magnitude of displacement, and θ = Angle between the vector of force and vector of displacement.

Unit of Work:

The SI unit for the work is the joule (J), and it is defined as the work done by a force of 1 Newton in moving an object for a distance of one unit meter in the direction of the force.

Work formula is used to measure the amount of work done, force, or displacement in any maths or real-life problem. It is written as in Newton meter or Nm.