1. No conversions. The greatest advantage of SI is that it has only one unit for each quantity (type of measurement). This means that it is never necessary to convert from one unit to another (within the system) and there are no conversion factors for students to memorize.

1 Answer. Multiply or divide by powers of 10. SI units are easy to convert because you multiply or divide by 10 – sometimes more than once. Think of a staircase – every time you step up a stair, you divide by 10; every time you step down a stair, you multiply by 10.

(i) It is a rational system, in which only one unit is used for one physical quantity. (ii) It is a coherent system, which means all the derived units can be easily obtained form basic and supplementary units. (iii) It is a metric system which means that multiples and submiltiples can be expressed as powers of 10.

Though it has great advantages and now we use SI units for most of the measurements but it is not free from disadvantages too. It has disadvantages such as it mainly focuses on only one unit so the importance of other units is diluted. Also the SI unit cannot always accurately define a quantity.

Deceleration always refers to acceleration in the direction opposite to the direction of the velocity. Deceleration always reduces speed. Negative acceleration, however, is acceleration in the negative direction in the chosen coordinate system.

Deceleration is the opposite of acceleration. Deceleration also is known as negative acceleration. Hence it is denoted by – a. It is the final velocity minus the initial velocity, with a negative sign in the result because the velocity is decreasing.

A concave up position versus time graph has positive acceleration. The vertex of this parabola is a point where the slope of the graph goes to zero. A point of zero slope in a position vs. time graph implies that the velocity goes to zero at that time.

If the object is speeding up, then its acceleration vector is directed in the same direction as its motion (in this case, a positive acceleration). The acceleration-time graph shows a horizontal line in the positive region of the graph (positive acceleration).

A positive acceleration means an increase in velocity with time. negative acceleration means the speed reduces with time. When the car slows down, the speed decreases. When an object is speeding up, the acceleration is in the same direction as the velocity.

Retardation is nothing but a negative acceleration. The change in velocity is known as acceleration. If the velocity of the body increases, acceleration is said to be positive. Similarly, if the velocity decreases, the acceleration is said to be negative.

Acceleration is the increase in velocity per second, while retardation is the decrease in velocity per second. Thus, retardation is negative acceleration. In general, acceleration is taken positive, while retardation is taken negative.

Hint: The increase in velocity per second is acceleration, whereas the decrease in velocity per second is retardation. Retardation, therefore, is negative acceleration. Acceleration is generally taken positively, while retardation is taken negatively.

Negative Acceleration is called Retardation, or Deceleration.

a = Change in velocity/Time taken So, you can get a negative acceleration value in the case of vretardation.

Acceleration (a) is the change in velocity (Δv) over the change in time (Δt), represented by the equation a = Δv/Δt. This allows you to measure how fast velocity changes in meters per second squared (m/s^2). Acceleration is also a vector quantity, so it includes both magnitude and direction.

a= u – v/t it is formula of retardation.