A girl walks 4km towards west, then she walks 3 km in a direction `30^@`east of north and stops. Determine the girls displacement from her initial point of departure.

Represent graphically a displacement of 40 km,30^@ east of north.

A wire placed along east, west direction carries a current of 5A from west to east direction. Determine the magnetic field due to a 1.8 cm piece of wire at a point 150 cm north, east from the piece?

A man is walking towards a vertical pillar in a straight path , at a uniform speed . At a certain point A on the path he oberves that the angle of elevation of the top of the pillar is 30^(@) .After walking for 10 minutes from A in the same direction , at a point B , he observes that the angle of elevation of the top pillar is 60^(@) .Then the time taken (in minutes) by him , from B to reach the pillar , is