An elevator weighing $6000\, kg$ is pulled upward by a cable with an acceleration of $5\, m/s^2$. Taking $g$ to be $10\, m/s^2$,then the tension in the cable is ........... $N$.

$A$ small ball of mass $m$ is released at a height $R$ above the Earth's surface,as shown in the figure. The ball enters a narrow groove and reaches a maximum depth of $R/2$ inside the Earth before coming to rest momentarily. The groove contains an ideal spring of spring constant $K$ and natural length $R$. Find the value of $K$. ($R$ is the radius of the Earth and $M$ is the mass of the Earth).

Which of the following is not an embryophyte?

The maximum value of ${x^4}{e^{ - {x^2}}}$ is

$A$ tetrahedron has vertices at $O(0, 0, 0)$,$A(1, 2, 1)$,$B(2, 1, 3)$,and $C(-1, 1, 2)$. The angle between the faces $OAB$ and $ABC$ is:

The number of significant figures in $23.023$,$0.0003$,and $2.1 \times 10^{-3}$ are respectively: