Why can it be said that there is no such thing as an isolated force in nature?

In a force $F$ versus time $t$ graph for an object,the area enclosed in a time interval of $1 \ s$ is $100 \ Ns$. Calculate the magnitude of the force. (in $N$)

Explain "Momentum gives more information than velocity alone".

$A$ ball of mass $400\, g$ is dropped from a height of $5\, m$. $A$ boy standing on the ground hits the ball vertically upwards with a bat with an average force of $100\, N$ so that it reaches a height of $20\, m$. For how long does the ball remain in contact with the bat (in $, s$)? $[g = 10\, m/s^2]$

Figures $(a)$,$(b)$,$(c)$ and $(d)$ show the variation of force with time. The impulse is highest in which figure?

$A$ time-varying force acts on a ball of mass $100 \ g$ for $2 \ ms$. The force versus time curve is shown below. If the initial speed of the ball is $10 \ m \ s^{-1}$,then the speed of the ball after $2 \ ms$ is: (in $m \ s^{-1}$)