Discussion on IIT-JEE

Speed is the rate of motion, or the rate of change of position. It is expressed as distance moved (d) per unit of time(t).Speed is a scalar quantity with dimensions distance/time. Speed is measured in the same physical units of measurement as velocity, but does not contain an element of direction. Speed is thus the magnitude component of velocity. Velocity contains both the magnitude and direction components. Acceleration, (symbol: a) is defined as the rate of change of velocity. It is thus a vector quantity with dimension length/time2. In SI units, acceleration is measured in meters/second2. To accelerate an object is to change its velocity, which is accomplished by altering either its speed or direction (like in case of uniform circular motion) in relation to time. Acceleration can have positive and negative values. Any time that the sign (+ or -) of the acceleration is the same as the sign of the velocity, the object will speed up. If the signs are opposite, the object will slow down. Acceleration is a vector quantity. When either velocity or direction changes, there is acceleration (or deceleration).

 abe simple mein sun...

kisi instant par jo speed hoti hai use instantaneous speed kehte hain...

sign convention k hisaab se sign laga diyo to instantaneous vel. ho jaayegi..

or kisi instant par ke acc. ko instantaneous acceleration kehte hain.....

PS: hope yu knoe the meanin' of instant..??