# Designing a toy rocket to be launched by a spring

In summary, the conversation is discussing the design of a toy rocket launched by a compressed spring. The spring has a compression of 14 cm and the rocket has a mass of 65 g. The goal is for the rocket to reach an altitude of 35 m. By setting the potential energy of the spring equal to the potential energy gained by the rocket, the spring constant can be calculated. However, the answer may differ due to incorrect unit conversions.
You're designing a toy rocket to be launched by a spring. The launching apparatus has room for a spring that can be compressed 14 cm, and the rocket's mass is 65 g. If the rocket is to reach 35 m altitude, what should be the spring constant?

$$U_o = 1/2*kx^2$$
$$K_o = 0$$
well work is being stored so K = 0 and U has the spring energy right?

$$U_f = mgh$$
$$K_f = 0$$

U_f = mgh because of the gravitational potention energy right? and K_f = 0 because it's at rest right when it reaches 35m? I'm not sure if K_f = 0 or not because i don't really know if the rocket is at it's max height when it reaches 35m.

well, setting them equal to each other...
$$1/2*kx^2 = mgh$$ and solving for k, i get 3.1 but the book gets 2.3 kN/M. what am i doing wrong?

You're designing a toy rocket to be launched by a spring. The launching apparatus has room for a spring that can be compressed 14 cm, and the rocket's mass is 65 g. If the rocket is to reach 35 m altitude, what should be the spring constant?

$$U_o = 1/2*kx^2$$
$$K_o = 0$$
well work is being stored so K = 0 and U has the spring energy right?

$$U_f = mgh$$
$$K_f = 0$$

U_f = mgh because of the gravitational potention energy right? and K_f = 0 because it's at rest right when it reaches 35m? I'm not sure if K_f = 0 or not because i don't really know if the rocket is at it's max height when it reaches 35m.

well, setting them equal to each other...
$$1/2*kx^2 = mgh$$ and solving for k, i get 3.1 but the book gets 2.3 kN/M. what am i doing wrong?
Your work is correct except for UNITS. Recalculate ALL quantities in MKS (meter, kg, sec) units, and you'll obtain the book answer.

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Last edited:

Your calculations and approach are correct. The book may have rounded the answer to 2.3 kN/M for simplicity. It is also possible that there was a typo in the book. It is always good to double check your work and use multiple sources for confirmation. Good job on solving the problem!

## 1. How do you determine the appropriate size and weight for the toy rocket?

The size and weight of the toy rocket should be determined based on the strength and force of the spring that will be used to launch it. It should be light enough to be launched effectively, but also heavy enough to provide stability during flight. Factors such as wind resistance and trajectory should also be taken into consideration.

## 2. What materials are best for building a toy rocket to be launched by a spring?

The materials used should be lightweight, yet durable enough to withstand the force of the spring. Some commonly used materials include lightweight plastics, foam, and balsa wood. It is important to choose materials that will not add too much weight to the rocket, but also provide enough structural integrity for a successful launch.

## 3. How do you ensure the safety of the toy rocket during launch?

Safety is a top priority when designing a toy rocket. It is important to use materials that are not sharp or hazardous to handle. The rocket should also be designed to have a stable and balanced flight, minimizing the risk of it veering off course and potentially causing harm. Additionally, it is important to launch the rocket in a wide open area away from people and buildings.

## 4. How can you incorporate educational elements into the design of the toy rocket?

There are many educational elements that can be incorporated into the design of a toy rocket launched by a spring. This could include teaching about the forces of motion, the laws of physics, and principles of engineering. The design could also include measuring tools and data collection devices to encourage hands-on learning and experimentation.

## 5. What are some troubleshooting tips if the toy rocket does not launch as planned?

If the toy rocket is not launching as planned, there could be a few potential issues to troubleshoot. First, check that the spring is properly attached and has enough tension to launch the rocket. Also, make sure the rocket is balanced and not too heavy. Adjustments to the design, such as adding fins for stability or adjusting the weight distribution, may also be necessary. It is also important to consider environmental factors such as wind and launch surface. If all else fails, try experimenting with different springs or materials to find the best fit for your design.

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