Name the physical quantity whose $SI$ unit is "newton".

When balanced forces act on a body,the body is

What are the changes possible on an object at rest if we apply on it:
$(a)$ a balanced force?
$(b)$ an unbalanced force?

$A$ $8000 \,kg$ engine pulls a train of $5$ wagons,each of $2000 \,kg$,along a horizontal track. If the engine exerts a force of $40000 \,N$ and the track offers a friction force of $5000 \,N$,then calculate the net accelerating force (in $N$).

$A$ force can be completely described by

Define $(i)$ force $(ii)$ dyne $(iii)$ newton.