$A$ body of mass $2 ~kg$ starts from rest and moves with uniform acceleration. It acquires a velocity $20 ~ms^{-1}$ in $4 ~s$. The power exerted on the body in $2 ~s$ in watts is

In the photoelectric effect,if the work functions of $Li$,$Na$,and $Rb$ are $2.41 \ eV$,$2.30 \ eV$,and $2.09 \ eV$ respectively,what could be the approximate work function of $K$ in $eV$?

What is the percentage of lead in a lead pencil (in $\%$)?

An aircraft executes a horizontal loop with a speed of $150 \, m/s$ with its wings banked at an angle of $12^\circ$. The radius of the loop is .......... $km$. $(g = 10 \, m/s^2)$

The horizontal acceleration that should be given to a smooth inclined plane of angle $\theta = \sin^{-1}\left(\frac{1}{l}\right)$ to keep an object stationary on the plane, relative to the inclined plane is:

Three rods of equal lengths are joined to form an equilateral triangle $ABC$. $D$ is the mid-point of $AB$. The coefficient of linear expansion is $\alpha_1$ for the material of rod $AB$ and $\alpha_2$ for the material of rods $AC$ and $BC$. If the distance $DC$ remains constant for small changes in temperature,then