Rocket motion Definition and 25 Threads

So according to this if you need a force that can lift a human and even an extremely ultra-light craft (1500 N) and have a velocity of 200 m/s you can eject extremely small amount of fuel through the nozzle: 0.0007 or less kg per second for as long as you're using 15 MPa pressure which is doable...

Basically it's a well known reaction, many kids on youtube make it for the views: I am thinking, since AlI3 sublimes can it be put in say tungsten bottle (is this even a thing??) and then used as a rocket the same way Na+H2O or HCL+Al rockets are used - the gas escapes? This phase...

Consider a rocket with mass ##m## in space is going to move forward. In order to do so, it needs to eject mass backwards. Let the mass that is ejected has velocity ##u## relative to the rocket. What is the equation for the final velocity? It is said that after ##dt## second, the rocket will...

Hello! I have recently found this fascinating article: https://zenodo.org/record/3596173#.YJ1ttV0o99B The author claims that classical equation for rocket thrust in incorrect because F is not equal to ma for a changing mass. Neither my professors nor me can see any errors. Do you think this...

I am using the derivative of momentum (dp/dt) with Newton’s 3rd Law with the gravitational force of Earth. F - [Force of gravity on rocket] = dp/dt F - (G * m_e * m_r / r2 ) = v * dm/dt + ma F = Force created by fuel (at time t) G = Gravitational Constant m_e = Mass of Earth m_r = Mass of...

Homework Statement While solving equation of rocket motion with Newton's law in 1-d,I pondered to apply Lagrangian method on this. However, I didn't get correct result. Because I can eliminate last 2nd equation using last equation and get some other equation which is certainly not rockets...

Homework Statement I want to try to derive the rocket equation and then add additional effects like gravity, air resistance, etc. Here's the equation that I found online: Homework Equations p (momentum) = mass * velocity F (force) = Δp / Δt The Attempt at a Solution [/B] pi = mv Here is...

The problem states: Typical chemical fuels yield exhaust speeds of the order of 103 m/s. Let us imagine we had a fuel that gives v0 = 3 × 105 m/s. What initial mass of fuel would the rocket need in order to attain a final velocity of 0.1c for a final mass of 1 ton? I derived the equation in the...

Homework Statement A rocket with initial mass of m0. The engine that can burn gas at a rate defined by m(t)=m0-αt, and expel gas at speed (relative to the rocket) of u(t)=u0-βt. Here, m0, α, u0, and β are all constants. Assume the lift-off from ground is immediate a) The rocket speed v(t)=...

Homework Statement I am trying to model a water rockets motion using a computer programme in order to compare it to my experimental data. I am studying physics at degree level but I have no knowledge of programming and am finding this particularly difficult. I have thought about using...

So suppose an astronaut in interstellar space has gas ejecting from her propulsion system. So the gas would cause her to move forward by some distance, d. Then, the F_{thrust} acting on her must be constant (assuming the amount of gas ejected per unit time is constant, and the speed it is...

Homework Statement Consider a rocket is subject to linear resistive force, f = -bv . \dot m is constant. Use the equation: m \dot{v} = -\dot{m }v + f to determine the velocity of the rocket : since the rate of mass lost is constant let \dot{m} =k vex = nuzzle velocity v = \frac{k}{b}...

Homework Statement Find the speed v of the rocket when the mass of the rocket = m. The rocket starts from rest at with mass M. Fuel is ejected at speed u relative to the rocket. Homework Equations m1v1 = m2v2 The Attempt at a Solution In the textbook, it starts off with a moving...

I'm trying to solve a rocket problem and have found no clear answer on how to do this. If I have a rocket in space (no significant gravitational forces, no drag, etc.) with a known constant thrust (T), mass flow rate (mdot), exhaust velocity (Ve), total initial mass including propellant (Mi)...

In the consideration of rocket motion we always use the principle of the Conservation of Linear Momentum.This principle holds true only for isolated systems.But the initial stage of rocket motion is strongly affected by gravity-----which is definitely an external force [if we consider the rocket...

Homework Statement What is the acceleration of the rocket at a time of 5seconds after the parachute opens. Homework Equations F=ma The Attempt at a Solution I simply thought the acceleration would be 9.8m/s/s

Hi there I'm having a bit trouble understanding the rocket motion and how the find the velocity, acceleration and travelheight as a function of time. First, i assume that the velocity of the ejected mass relative to the rocket is constant. Secondly, i assume that the rocket mass changes with...

Homework Statement A rocket is traveling with a speed 20 km/s in a non-gravity space. To fix the direction of motion, it turns on an engine, which pushes the gasses with constant speed 3 km/s w.r.t. the rocket perpendicularly to the direction of its motion. The engine is on till the mass of...

Homework Statement A rocket of initial mas M, of which M-m is fuel, burns its fuel at a constant rate in time tau and ejects the exhausts gases with constant speed u. The rocket starts from rest and moves vertically under uniform gravity . Show that the maximum speed achieved by the rocket...

A toy rocket moving vertically upward passes by a 2.2 m high window whose sill is 9.0 m above the ground. The rocket takes 0.14 m/s} to travel the 2.2 m height of the window. What was the launch speed of the rocket? Assume the propellant is burned very quickly at blastoff. How high will...

Homework Statement A rocket on its launch pad has a mass of 20,000kg. The engine fires at t=0s and produces a constant force of 500,000 N straight up. The engines fire for 1 minute during which the entire 10,000kg of fuel on poard is consumed and expelled from the rocket at a constant rate...

1. A shuttle bus slows down with an average acceleration of -1.8m/s^2. How long does it take the bus to slow from 9.0m/s to a complete stop? For this question, we can immediately say that the final velocity is 0m/s because it stops. Now let's take a look at the second question: A robot probe...

Ok here's a question i had for homework, but i am having some trouble with it: a rocket is fired from rest with an acceleration at=22.8m/s at an elevation angle of theta=62.4. the rocket travels in a straightline for 8.95 seconds, when the fuel runs out. at this time it becomes a projectile...

For a rocket in free space, it seems that P = mv + (m_0 - m)(v-u) where m is the mass of the rocket, v is its speed, m_0 is its initial mass, u is the speed of the propellent relative to the ship. But in solving dP/dt=0, I get that the velocity is linear in m. There seems to be a mistake...

This question was posed in class the other day for extra credit: A rocket with initial mass 70000kg burns fuel at a rate of 250kg/s; it has an exhaust velocity of 2500m/s. If the rocket is at rest, how long after the engines fire will the rocket lift off? I've been trying to solve it...