A rocket has a per-ignition mass of 1100kgs-1 producing a thrust of 10000N. How long after ignition of the fuel will the rocket lift off?

also explain how is it possible for a rocket to accelerate in space.
(i cant work it outt. i know it involves the rocket thrust equation some how, the newtons 2nd law and suvat's..) thank you

You must have misspelled and omitted something.

I assume you mean pre-ignition mass, not per-ignition mass, which makes no sense.

If so, what is the pre-ignition mass? The number you have provided is a mass flow RATE.

The rocket lifts off then the trust equals the weight. Use the initial mass and the mass flow rate to figure out when that happens.

i haveeee!! ive posted the right question again please look it up again if you have time :(

To find out how long after ignition the rocket will lift off, we need to understand the concept of acceleration and apply Newton's second law of motion.

Newton's second law states that the force acting on an object is equal to the mass of the object multiplied by its acceleration. Mathematically, this can be written as F = m * a, where F is the force, m is the mass, and a is the acceleration.

In the case of a rocket, the force (thrust) produced by the engine is equal to the mass of the rocket multiplied by the acceleration of the rocket.

Given that the rocket has a per-ignition mass of 1100 kg/s and a thrust of 10000 N, we can calculate the acceleration using Newton's second law.

Using F = m * a, we can rearrange the equation to find the acceleration (a) as a = F / m.

a = 10000 N / 1100 kg/s
a ≈ 9.09 m/s²

Now that we know the acceleration, we can determine the time it takes for the rocket to lift off using the equations of motion (SUVAT equations).

One of the SUVAT equations that relates acceleration (a), initial velocity (u), time (t), and displacement (s) is s = ut + 0.5at², where s is the displacement.

When the rocket lifts off, its initial velocity is zero, and its displacement (s) is the height it needs to cover before achieving lift-off.

Assuming the rocket lifts off vertically, we can set the displacement (s) to the height of lift-off. Let's assume the height is h meters.

Using the SUVAT equation s = ut + 0.5at² and substituting the initial velocity (u) as zero, the equation becomes:

s = 0 + 0.5at²
h = 0.5at²

Rearranging the equation to find time (t), we get:

t² = (2h) / a
t = √((2h) / a)

Substituting the values of a = 9.09 m/s² and the given height of lift-off (h), we get the answer for how long after ignition the rocket will lift off.

As for how a rocket accelerates in space, it's important to note that a rocket, unlike most vehicles on Earth, does not rely on wheels or any external surface for propulsion. Instead, rockets work on the principle of action and reaction known as Newton's third law of motion. According to this law, for every action, there is an equal and opposite reaction.

In the case of a rocket, burning fuel in the combustion chamber produces hot gases that are expelled through the rocket nozzle at high speeds. According to Newton's third law, the ejection of these gases generates an equal and opposite force known as thrust, propelling the rocket forward. Since there is no air resistance or friction in space, this thrust continues to accelerate the rocket. By continuously expelling gases at high velocity, the rocket gains momentum and accelerates in the opposite direction.

Thus, a rocket is able to accelerate in space by relying on the expulsion of gases that generate a reactive force, allowing it to move forward without the need for an external surface to exert force against.