## Displacement Problem

A particle has a displacement of 12 m towards east and 5 m towards north and then 6 m vertically up. Find the magnitude of the resultant of these displacements.

The resultant of the first two displacements – 12 m and 5m in mutually perpendicular directions is

$\sqrt{\left&space;(&space;12^{2}+5^{2}&space;\right&space;)}=13$ m

The resultant of 13m and 6m in mutually perpendicular directions is

$\sqrt{\left&space;(&space;13^{2}+6^{2}&space;\right&space;)}=14.32&space;m$

## Kinematics – Signs of displacement and Velocity

When will displacement and velocity be negative ? Can you explain me about angular acceleration and angular velocity.

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The signs are conventional. We take one direction as positive and the direction opposite to it as negative.

When we discuss one-dimensional motion, it is easy to take the help of the number-line, whatever towards right is positive and towards left is negative. If the initial direction of motion is taken as positive and the further displacements does not make the body to go beyond the initial position in opposite direction, the displacement will be positive.

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## Displacement – A Numerical Problem

A fly is sitting in the middle of a wall of a cubic room of side ’a’.If it flies and sit to one of opposite corner of the wall. Find its displacement?

If the fly sit on the same wall on the horizontal, (from A to B in the diagram) the displacement is “a
If the fly sits on the diagonally opposite corner on the same wall, (from A to C in the diagram) the displacement is “√2 a
If the fly sits on the corner on the longest diagonal of the room,  (from A to H in the diagram) the displacement is “√3 a

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