Page 5 - Lesson Notes (Motion in a Plane)

(vi) Vector product in cartesian coordinates

Direction of Vector Cross Product
When C = A * B, the direction of C is at right angles to the plane containing the vectors
A and B. The direction is determined by the right hand screw rule and right hand thumb
rule.

(i) Right Hand Screw Rule Rotate a right handed screw from first vector (A) towards
second vector (B). The direction in which the right handed screw moves gives the
direction of vector (C).
(ii) Right Hand Thumb Rule Curl the fingers of your right hand from A to B. Then, the
direction of the erect thumb will point in the direction of A * B.

Projectile

A body which is in flight through the atmosphere but is not being propelled by any fuel
is called projectile. Example: (i) A bomb released from an aeroplane in level flight(ii) A
bullet fired from a gun