The energy of $$E$$ of a system is function of time $$t$$ and is given by $$E(t)=\alpha t-\beta t^3$$, where $$\alpha$$ and $$\beta$$ are constants. The dimensions of $$\alpha$$ and $$\beta$$ are
A student is at a distance 16 m from a bus when the bus begins to move with a constant acceleration of $$9 \mathrm{~m} \mathrm{~s}^{-2}$$. The minimum velocity with which the student should run. towards the bus so as the catch it is $$\alpha \sqrt{2} \mathrm{~ms}^{-1}$$. The value of $$\alpha$$ is
The component of a vector $$\mathbf{P}=3 \hat{i}+4 \hat{j}$$ along the direction $$(\hat{i}+2 \hat{j})$$ is
A projectile is launched from the ground, such that it hits a target on the ground which is 90 m away. The minimum velocity of projectile to hit the target is (acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)