Question:

A particle moves from position \(3\hat{i}+2\hat{j}+6\hat{k}\) to \(14\hat{i}+13\hat{j}+9\hat{k}\) due to a uniform force of \(4\hat{i}+\hat{j}+3\hat{k}\,N\) . Find the work done, if the displacement is in metre.

Updated On: Sep 4, 2023
  • 16 J
  • 64 J
  • 32 J
  • 48 J
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The Correct Option is B

Solution and Explanation

The correct answer is B:64 J
Work done \(= F \cdot d\)
\(= (4 \hat i + \hat j + 3 \hat k) \cdot[(14 - 3) \hat i + (13 - 2) \hat k + (9 - 6) \hat k]\)
\(= (4 \hat i + \hat j + 3 \hat k)\cdot (11 \hat i + 11 \hat j + 3 \hat k)\)
\(= 44 + 11 + 9 = 64 \, J\)
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Concepts Used:

Motion in a Plane

It is a vector quantity. A vector quantity is a quantity having both magnitude and direction. Speed is a scalar quantity and it is a quantity having a magnitude only. Motion in a plane is also known as motion in two dimensions. 

Equations of Plane Motion

The equations of motion in a straight line are:

v=u+at

s=ut+½ at2

v2-u2=2as

Where,

  • v = final velocity of the particle
  • u = initial velocity of the particle
  • s = displacement of the particle
  • a = acceleration of the particle
  • t = the time interval in which the particle is in consideration