00:00Question is, a body moves due east with velocity 20 km per hour and then due north with velocity
00:1715 km per hour. The resultant velocity is, a 5 km per hour, b 15 km per hour, c 20 km per hour, d 25 km per hour.
00:36Suppose, this is a direction indicator, this is north, this is south, this is east and this is west.
00:47Question is, a body is moving with a velocity of 20 km per hour towards east, this is point A and this is point B.
01:07So, then the body turns from point B and moves with a velocity of 15 km per hour towards north.
01:17So, the resultant velocity will be,
01:34So, we have to find resultant velocity. So, to find the resultant velocity, we will use the Pythagoras theorem,
01:47which is equal to, V is equal to under root, Vx square plus Vy square,
01:55because this is the x component of velocity and this is y component of velocity.
02:03So, the magnitude of velocity will be, means resultant velocity will be, Vx is 20, so the square on 20 plus Vy is 15, so the square on 15.
02:17So, resultant velocity will be obtained as, the square of 20 is 400, the square of 15 is 225, so it will be, V will be equal to 400 plus 225, it will be under root 625,
02:39is the under root of 625 is 25. So, the velocity will be obtained as 25 km per hour. So, the correct option will be D, 25 km per hour.
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