Physics - Online Test

Torque = Force x Perpendicular distance of the line of action of the force from the axis of rotation. It is also called moment of force.

 torque is defined as the cross product of the vector by which the force's application point is offset relative to the fixed suspension point (distance vector) and the force vector, which tends to produce rotational motion.

τ⃗ =r⃗ ×F⃗ 

A unit vector in a normed vector space is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat": i^ (pronounced "i-hat"). The term direction vector is used to describe a unit vector being used to represent spatial direction.

i^=a unit vector directed along the positive x axis

j^= a unit vector directed along the positive y axis

k^ = a unit vector directed along the positive z axis

The SI unit of quantity of electric charge is the coulomb, which is equivalent to about 6.242×1018 e (e is the charge of a proton).

Hence, the charge of an electron is approximately −1.602×10−19 C. The coulomb is defined as the quantity of charge that has passed through the cross section of an electrical conductor carrying one ampere within one second. The symbol Q is often used to denote a quantity of electricity or charge.