- A diagonal matrix is a square matrix where all off-diagonal elements are zero. The diagonal elements can be non-zero.
- A symmetric matrix \(A\) satisfies \(A' = A\), meaning it is equal to its transpose.
- A skew symmetric matrix has all diagonal elements equal to zero. - A row matrix has only one row, as the name suggests.
Thus, the statement "A diagonal matrix has all diagonal elements equal to zero" is false because the diagonal elements can be any value.
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)):