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When the rocket reaches the position in its trajectory shown, it has a mass of \(3 \mathrm{Mg}\) and is beyond the effect of the earth's atmosphere. Gravitational acceleration is \(9.60 \mathrm{m} / \mathrm{s}^{2}\). Fuel is being consumed at the rate of \(130 \mathrm{kg} / \mathrm{s},\) and the exhaust velocity relative to the nozzle is \(600 \mathrm{m} / \mathrm{s}\). Compute the \(n\) - and \(t\) -components of acceleration of the rocket.

Short Answer

Expert verified
The t-component of acceleration is 16.4 m/s²; the n-component is 0 m/s².

Step by step solution

01

Identify Known Values

Given the mass of the rocket is 3 Mg, which is equivalent to 3000 kg. The gravitational acceleration is 9.60 m/s². The fuel consumption rate is 130 kg/s, and the exhaust velocity is 600 m/s.
02

Calculate Mass Rate of Change

The mass rate of change \( \frac{dm}{dt} \) is equal to the fuel consumption rate, \( \frac{dm}{dt} = -130 \) kg/s. The negative sign indicates that the mass is decreasing as fuel is burned.
03

Apply Rocket Equation

Using the rocket thrust equation, the thrust force \( F_{t} \) is calculated as the product of the mass rate of change and the exhaust velocity: \[ F_{t} = -\left( \frac{dm}{dt} \right) v_{e} = 130 \cdot 600 = 78000 \text{ N} \]
04

Calculate Total Acceleration

The net force acting on the rocket includes thrust and gravitational force. The gravitational force \( F_{g} \) is \( m g \), where:\[ F_{g} = 3000 \cdot 9.60 = 28800 \text{ N} \]. The net force \( F_{net} \) is given by: \[ F_{net} = F_{t} - F_{g} = 78000 - 28800 = 49200 \text{ N} \]. This force acts in the direction of the thrust (t-component).
05

Find T-Component of Acceleration

The t-component of acceleration \( a_{t} \) is obtained by using Newton's second law, \( F = ma \): \[ a_{t} = \frac{F_{net}}{m} = \frac{49200}{3000} = 16.4 \text{ m/s}^{2} \].
06

Determine N-Component of Acceleration

Since the rocket is beyond atmospheric effects and no lateral forces are mentioned, the n-component of acceleration is 0 m/s².

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Rocket Propulsion
Rocket propulsion is the principle that enables a rocket to move forward by expelling exhaust gases. This is based on Newton's third law of motion, which states every action has an equal and opposite reaction. Here, the force exerted by the rocket on the expelled gases results in an equal force in the opposite direction, propelling the rocket forward.
Propulsion involves a few key components:
  • Fuel: The rocket carries a supply of fuel which, when burned, creates high-speed exhaust gases.
  • Nozzle: The narrow nozzle at the end of the rocket accelerates the exhaust gases, allowing them to exit at high velocities.
  • Thrust: The thrust force is calculated as the product of the mass rate of change of the rocket and the exhaust velocity. The formula is given by: \[ F_t = rac{dm}{dt} \cdot v_e \] where \( v_e \) is the exhaust velocity and \( \frac{dm}{dt} \) is the rate of mass loss due to burning fuel.
The greater the exhaust velocity and the faster the mass of fuel is evacuated, the greater the thrust, leading to higher acceleration of the rocket.
Gravitational Acceleration
Gravitational acceleration (often denoted as \( g \)) is the acceleration due to the gravitational force exerted by the Earth. On the surface of the Earth, this value is approximately \( 9.81 \text{ m/s}^2 \). In this exercise, it is given as \( 9.60 \text{ m/s}^2 \) perhaps due to a specific location or some other context. This constant acceleration acts downwards towards the center of the Earth and affects all objects that have mass, including rockets.
For a rocket, gravitational acceleration is crucial because it counteracts the thrust generated by rocket propulsion. To move upward, the rocket's thrust must not only equal the gravitational force acting upon it but exceed it to achieve acceleration. Logging these forces mathematically:
  • Gravitational Force: \( F_g = m \cdot g \)
  • Net Force: The net force is given by the equation \( F_{net} = F_t - F_g \). This net force is what results in the movement and acceleration of the rocket.
Understanding gravitational acceleration is key in planning a successful rocket launch and ensuring it reaches the desired velocity and altitude.
Newton's Laws of Motion
Newton's laws of motion are fundamental principles that describe the relationship between an object and the forces acting upon it. They help explain how rockets move beyond Earth's atmosphere. Here, the key laws in play are:
  • First Law (Law of Inertia): A rocket at rest will stay at rest, and a rocket in motion will stay in motion, unless acted upon by an external force. A rocket needs an initial push (thrust) to overcome inertia.
  • Second Law: States that the acceleration of an object is proportional to the net force acting on it and inversely proportional to its mass. It's expressed as \( F = ma \). For a rocket: \[ a_t = \frac{F_{net}}{m} \] Here, the greater the net force compared to mass, the greater the acceleration. This principle was used to find the t-component of the rocket's acceleration in the solution.
  • Third Law: For every action, there is an equal and opposite reaction. The rocket's propulsion system is based on this law, where the expulsion of gases results in the thrust that moves the rocket.
These laws are critical as they guide engineers in ensuring that rockets have the ideal specifications for successful launch and travel through space.

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Most popular questions from this chapter

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