# What is Thrust force: Definition and 23 Discussions

Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system.
The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust.

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### Sci-fi engine thrust calculations

Hi all, I'm writing a technical manual for a starship in a science-fiction series I'm working on, I wanted to check with some folks here to make sure my calculations are correct concerning the ship's engine thrust. The ship has a fully-loaded mass of 5 million metric tons. Using its...
2. ### Doubt related to buoyant force and fluid thrust force

(this problem is slightly modified from the original problem.) There is a contact force(friction and normal force) between the wedge and the walls of the container and there is a fluid thrust acting on the side of the wedge in contact with the fluid( this force is normal to the slanted surface...
3. ### Effect of thrust force on torque?

If I have a motor that is turning a shaft with only a small torque required but the shaft is also being forced into the motor, axially at a large force, what is the effect on the motor here? If Faxial is large, does this effect T and how does this effect the motor?
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### Exhaust velocity of a fire extinguisher

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hey, For our project we have to think of an experiment that can kind of simulate a rocket. We decided to use a fire extinguisher on a kart, since its mass constantly changes (same with a rocket)...
5. ### Rocket thrust force calculation

Homework Statement A rocket has weight 10,000 kg and it needs to carry 5000 kg with acceleration 3.5 m/s². How much thrust force is necessary for the rocket to have a flight from Earth to space? Homework Equations F=ma[/B]The Attempt at a Solution I try that, According to Newton's law, (...
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### The total moment when rolling

Hey, everyone, I have a question regarding quadcopters, when the set of the arms is of configuration X, to roll we increase the velocity of the two motors on the left/right and decrease the other motors on right/left, the question is when doing so the total angular velocity is zero that means...
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### Relating propeller thrust, power, and rpm together

Hi All, I am involved in a research project regarding electric aircraft. I've done a fair bit of research into this but am having trouble keeping all the different parameters and how they affect each other straight in my head. Fundamentally I am putting together a model whose parameters I can...
8. ### Lift vs Thrust Force: How Is More Lift Than Thrust Possible?

The thrust of an airplane changes the speed of the airplane, or you can look at it as it is increasing the airspeed relative to the airplane. The airspeed across the wings is only as much as the thrust allows it to be. The airspeed across the wing is what produces thrust, and I realize how it...
9. ### Thrust of an underpressure tank of air

How can I calculate the thrust of an underpressure tank of air when the valve is released? If you can, please, explain in detail. Thank you!
10. ### What Is the Required Thrust Force to Launch a 590 kg Rocket?

Homework Statement A 590 kg rocket is at rest on the launch pad. What upward thrust force is needed to accelerate the rocket uniformly to an upward speed of 28 m/s in 3.3 s? Homework Equations V = Vi + at F = ma The Attempt at a Solution I'm just confused about what "thrust force" actually...
11. ### Work energy theorem problem

Homework Statement A uniform chain of mass m and length l overhangs on a smooth table with two third part lying on the table. Find the kinetic energy of the chain after it slips off the table. Homework Equations F=ma Total work done by all forces = change in kinetic energy The Attempt at a...
12. ### Maximum Thrust force in submarine

I am designing a submarine in low scale that the max propeller OD is 10 cm, means from center of shaft to propeller edge I have around 5 cm distance. I am trying to find the maximum thrust as this submarine suppose to pull an object inside water pipe. I need to find optimum rpm ,blade number...
13. ### Thrust force of a rocket ejecting mass

Homework Statement OK, this seems simple but I want to make sure I am not doing something totally wrong. The problem says: use the conservation of mass of a system of many particles to shoe that the thrust force of a rocket that ejects mass at rate \frac{dm}{dt} is equal to F=-v_e...
14. ### Understanding Thrust Force Basics

What is thrust?? can someone please give me a brief explanation about the thrust force?
15. ### How to calculate a jet pump thrust force?

hi everyone In order to calculate the thrust force of a jet pump , what must I know and what is the formula used? thanks :)
16. ### Regarding angular momentum axial thrust force etc. space stations

Disclaimer: I'm not a physicist nor do I know calculus, but I'd appreciate a little guidance with a concept I've been thinking about. I know one would usually pay for this kind of advice, but since it's just for entertainment, I'm not asking for any equations to be solved, unless you're in the...
17. ### Formula for thrust force on helicopter

can anyone please give me the formula to calculate the thrust force exerted by the rotor blades of the helicopter on the air
18. ### Why is the thrust force equal to the change in momentum of the rocket?

Hello People actually i want to make sure of this explanation The external force acting on the rocket is zero Therefore : F = mdv/dt+vdm/dt=0 Therefore mdv/dt=-vdm/dt=Fimp(Impulse force or thrust force) Well I have an explanation for this but I'm not sure about it The external...
19. ### Child jumps on a cart, cart slows down, find mass of the cart and thrust force

Homework Statement A cart is driving on straight tracks with a velocity of 2 m/s. In the opposite direction, with an angle of 60º according to the tracks, a child with a mass of 2 kg is running with a velocity of 2m/s, he jumps on the cart and stays there. - Find the mass of the cart, if its...
20. ### Calculating Average Thrust Force for Airplane Take-off

Homework Statement The take-off speed of a given airplane is 250 mi/h. If the take-off weight is 110,000 Kg, what is average the thrust force exerted by the engines? Homework Equations w=mg ,F=ma , F=mW The Attempt at a Solution the mi/h confuses me and I don't know which...
21. ### Calculate Rocket Thrust Force of 90g Rocket Achieving 80m/s in 3.0s

A toy rocket, of mass 90g, acheives a velocity of 80m/s after 3.0s when fired straight up. What average thrust force does the rocket engine exert? I dont' know what formula to use for this
22. ### Calculating Flight Angle and Thrust Force of a Gliding Plane with Engine Failure

Homework Statement A plane of mass 1220 kg has an engine failure when flying with an airspeed of 138 km/h at an altitude of 2960 m on a calm day. It then glides at a constant glide angle (which is the direction of flight below the horizontal) 6.80 degrees towards a safe landing at this...
23. ### Calculating Thrust Force of a Model Rocket

1. Homework Statement A model rocket of mass 4.8 x 10^2 g accelerates vertically upward at 34.m/s2. Calculate the thrust force applied by the rocket if the air resistance is 2.4N 2. Homework Equations F=ma? 3. The Attempt at a Solution Converted into SI rocket mass = 0.48g...