Question

The S.I. units of thrust is same as that of
A. Force/Area
B. Force $\times$ Area
C. Force
D. None of these

Answer 1

Hint: Thrust is a mechanical force. It is produced in aircrafts, rockets, etc. As per, Newton’s third law, every action has an equal and opposite reaction. This thrust force is caused as a reaction to expulsion of exhaust gases. Being a reaction force, it has the units same as force.

Complete answer:
Thrust is the force generated through expulsion of gases.
Consider rocket propulsion. As the fuels are burnt in the combustion chamber, they release gases through the exhaust pipe. These gases propel the rocket in forward direction.
The force applied by these gases is called thrust. Mathematically, it is given by
$F = {v_{exh}} \times \dfrac{{dm}}{{dt}}$
Where,
F is the thrust force
$v_{exh}$ is the exhaust velocity
m is the mass
t is the time
Clearly, we can see that thrust is a force. So, obviously it will have the same units as Force.

Hence, the correct option is C. Force

Additional Information:
S.I. units of force are given by N.

Note:
You can also solve this problem by using the formula
$F = {v_{exh}} \times \dfrac{{dm}}{{dt}}$
Here, the exhaust velocity has units m/s and the units of mass and time are kg and s, respectively. Multiplying the both units we have
$m.{s^{ - 1}} \times \dfrac{{kg}}{s} = 1kg.m.{s^{ - 2}} = 1N$
Since N (Newton) is the S.I. unit of force, thrust has the unit same as force.
Therefore, the correct option is C.