Under action of force, a 2 kg body moves such that its position $x$ as function of time $t$ is given by $x=\alpha t^2 / 2$, where $x$ is in metre, $t$ is in seconds and $\alpha=1 \mathrm{~m} / \mathrm{s}^2$. The work done by the force in the first two seconds is

A force of 4 N acts on a 10 kg body initially at rest. Let $W_1$ is work done by force during $0 \leq t \leq \mathrm{ls}$. Likewise $W_2$ is the work done by force during $\mathrm{l} \mathrm{s} \leq t \leq 2 \mathrm{~s}$, where $t$ is time in second. The ratio $\frac{W_2}{W_1}$ is

An elevator of mass 500 kg is ascending upwards with a constant acceleration $a=2 \mathrm{~m} / \mathrm{s}^2$. What is the work done by the tension in the elevator cable during its climb by 12 m ? (Take, $g=10 \mathrm{~m} / \mathrm{s}^2$ )

A force $\mathbf{F}=(2 \hat{\mathbf{i}}+4 \hat{\mathbf{j}}) \mathrm{N}$ is applied on an object of mass $M$. What is the work done by this force in moving the object horizontally along the $X$-axis by 3 m ?