Question

A rocket of mass $1000\, kg$ is exhaust gases at a rate of $4\, kg/s$ with a velocity $3000\, m/s$. The thrust developed on the rocket is :

• A. 12000 N
• B. 120 N
• C. 800 N
• D. 200 N

Answer 1

The Correct Option is A

\(m =1000\, kg\) \(\frac{\Delta m }{\Delta t }=4\, kg / s,\, v =3000\, m / s\) Thrust on the rocket \(F =- v \frac{\Delta M }{\Delta t }\) \(=-3000 \times 4\) \(=-12000\, N\) (Negative sign indicates that thrust applied in a direction opposite to the direction of escaping gas)

The sorts of forces that may be applied to a specific item are thrust and pressure. The direction of force application is the main distinction between the two. Any force may be applied to a surface in any direction. Pressure is the thrust or force applied to a unit area of surface, whereas thrust is the force applied to a surface in a direction that is normal to or perpendicular to the surface. The gravitational pull and gravity of the earth have an impact on both thrust and pressure. The two names are frequently used interchangeably and seem to mean the same thing at first glance. However, if we pay great attention, we can observe how unlike they are.

A force that affects an item called a thrust. There are several ways to exert force on an object. Pressure is the impact of thrust per unit area on an object, whereas thrust is the force that acts perpendicular to an item's surface. Maintaining a thing on a surface causes it to experience force. The region of contact with that surface determines how the force behaves on it. When the area is larger, the force has a lower impact (less pressure), and when the area is smaller, the force has a higher impact (more pressure).

The force that typically acts on a surface is known as thrust. A vector quantity, that is. 

Any direction can be used to apply pressure on a surface. 

When a body is put on a surface, the surface receives a push equal to the weight of the body. The push is the same regardless of where the body is on the surface.

The amount of force (push) exerted on a surface per unit area is referred to as pressure. Alternately, it may be thought of as the force divided by the area that it affects upon. 

Depending on the region of the surface it hits, pressure has varying consequences. In units of force per unit area, the pressure impact is quantified. It has a scalar value.

From the definition of thrust, we can conclude that,

Thrust = Pressure * Area

It is expressed in units of force. The newton (N) is the SI unit of thrust, while the dyne is the CGS unit. Also,

1N = 10⁵ dyne

In the MKS system, the gravitational unit of thrust is kgf, but in the CGS system, it is gf. Hence,

1 kgf = 9.8N 

1gf = 980 dyne