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The Little Rocket Sled That Could (Question Offered For Fun & Educational Value)?

The Little Rocket Sled That Could (Question Offered For Fun & Educational Value)? Topic: C case smaller than symbol
April 19, 2019 / By Garrick
Question: A little sled weighs one pound. It is set in motion over frictionless ice by a toy rocket motor. After the rocket fuel is expended, the sled is coasting over the ice at one foot per second. How much force did the rocket exert on the sled to make it go? a) 1 pound b) 4 pounds c) 16 pounds d) 32 pounds e) There is no way to tell from the information given. Choose one answer only please. A correct answer accompanied by a correct explanation trumps a correct answer alone (so first to answer doesn't exclude others from being selected for "Best Answer." I already know the answer (I think!) to the question. I offer it for the fun and educational value. I love to share physics puzzles that at once make a person think while simultaneously teaching basic physics concepts in a different and creative manner. My questions are meant for individuals of all levels of expertise. If you don't like a question (for whatever reason), just move on to another that suits you better. General Advice: Equations are useful abbreviations of relationships and are indispensable to the physcist. But often they are misused -- when they become substitutes for understanding. Never put your efforts toward memorizing equations until you understand the concepts the symbols represent. Only after a conceptual understanding are the equations truly meaningful. There are some terrific answers so far! Don't worry. I never ask a question that requires more than a basic knowledge of algebra. The concept is the important thing. Alexander: You're right. It's an honor to have someone who asks such excellent questions of their own answer one of my questions! Linlyons: It's always an educational experience. You have a talent for taking a question and probing deeper. Thank you! Vincent G: Thank you. Great explanation as well as a correct answer!!! BB: Strange but poetically creative! And correct! Aaron: Excellent work! I'm sorry I can only choose one best answer. Please try again. I very much appreciate your answer. It helped not only myself but others who are learning what you know. Now for my "official" explanation... The correct answer is E. That's right, you can't tell you say! The rocket motor might have provided a small force for a lng time or a big force for a short time, but from the information givein you can't tell which. This question is very much like asking how long is a rectangle which contains 12 square inches. It might be one long and twelve high or two long and six high or three long and four high. In the case of the sled, its moomentum is like the area of the rectangle and the force and time during which the force acts are like the sides of the rectangle which multiply together to make the area. Area = Height x Length Change in Momentum = Force x Time Thank you for your insightful answers and sharing your knowledge with others so that they can learn.
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Best Answers: The Little Rocket Sled That Could (Question Offered For Fun & Educational Value)?

Devereux Devereux | 8 days ago
e) there is not enough information A given force will create a given acceleration to a given mass, but the final speed is a function of how long that acceleration was maintained, and that depends on how much trust was produced. A thrust T that is applied for a time t will provide the same final speed as a thrust T/2 applied for a period of time 2t.
👍 144 | 👎 8
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Devereux Originally Answered: The Little Rocket Sled That Could (Question Offered For Fun & Educational Value)?
e) there is not enough information A given force will create a given acceleration to a given mass, but the final speed is a function of how long that acceleration was maintained, and that depends on how much trust was produced. A thrust T that is applied for a time t will provide the same final speed as a thrust T/2 applied for a period of time 2t.

Bernie Bernie
So the sled was propelled by all the dolls and toys together wishing it along to get the toys and good things to eat to the good little boys and girls. But unless you know how long the dolls and toys were wishing for, you can't tell how hard they were wishing even if you know the final momentum achieved.
👍 50 | 👎 -1

Abiram Abiram
according to me the answer is e. F=m*a m=1 pound a=(final velocity-initial velocity)/t a=(1-0)/t =1/t since we don't know the time we will not know the exact rate of acceleration and so we will get F=1a hence depending on the value of t we will get force as 1pound for t=1 0.5pounds for t=2 and so on.
👍 43 | 👎 -10

Sissy Sissy
C) two times as lots KE as first one by the conservation of capability, the aptitude capability of blocks at optimal ingredient is easily switched over to KE at backside,neglecting air resistance.for this reason, the PE of the 2nd block on the ideas-blowing(2 x mgh) is two times the PE of 1st block(mgh),for this reason the KE of the 2nd block would be two times that of 1st
👍 36 | 👎 -19

Phrona Phrona
I cannot tell you how much force, but I can tell you how much impulse of that force: 1/2 ounce x second.
👍 29 | 👎 -28

Phrona Originally Answered: To all nurses/cpn's/lpn's etc. Is this a good educational plan?
that would work. But I would skip step 1 and go to step 2. Hospitals are so eager for nurses they often pay for your schooling as long as you sign up to work for them for 2 years after graduation. They may let you work when you have time in some area of the hospital while you are in school. Some nursing homes do this, too. Don't go into nursing unless you talk to at least 5 nurses and get their view of their career. It's very hard!!! Most wish they had not gone into nursing.

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