- #1
FarisL
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So I got this question on a physics quiz:
"You have have two masses, M1 and M2, weighing 1.00 kg and 2.00 kg respectively. You have an ideal, massless spring (spring constant = 40.0 N/m) set up vertically from the ground with a massless platform attached to its free end on top. The two masses are gently placed on top of each other on the platform, so that the mass-spring system is at rest, with the platform's height set as zero relative to the system (for simpler calculations). Suddenly, the 2.00 kg mass is removed, causing the system to rebound vertically upwards. Find the maximum height the platform reaches."
You are first required to find the distance, x, the spring contracts when the two masses are placed on it, using kx = mg. Once you know that, you are to find the maximum height using the equation for the conservation of energy, Ek1+Eg1+Ee1 = Ek2+Eg2+Ee2, where Ek is the kinetic energy, Eg is the gravitational energy, and Ee is the elastic energy.
Now, both Ek1 and Ek2 are canceled out, as they equal zero. Eg1 is canceled out as well, as the height at that moment is zero as well. We are left with Ee1 = Eg2+Ee2.
My question: Is Ee2 canceled out or not?
I solved it using the two scenarios; if it is, you should get an answer of around 1.1 m. If not, you should get something like 0.981 m.
"You have have two masses, M1 and M2, weighing 1.00 kg and 2.00 kg respectively. You have an ideal, massless spring (spring constant = 40.0 N/m) set up vertically from the ground with a massless platform attached to its free end on top. The two masses are gently placed on top of each other on the platform, so that the mass-spring system is at rest, with the platform's height set as zero relative to the system (for simpler calculations). Suddenly, the 2.00 kg mass is removed, causing the system to rebound vertically upwards. Find the maximum height the platform reaches."
You are first required to find the distance, x, the spring contracts when the two masses are placed on it, using kx = mg. Once you know that, you are to find the maximum height using the equation for the conservation of energy, Ek1+Eg1+Ee1 = Ek2+Eg2+Ee2, where Ek is the kinetic energy, Eg is the gravitational energy, and Ee is the elastic energy.
Now, both Ek1 and Ek2 are canceled out, as they equal zero. Eg1 is canceled out as well, as the height at that moment is zero as well. We are left with Ee1 = Eg2+Ee2.
My question: Is Ee2 canceled out or not?
I solved it using the two scenarios; if it is, you should get an answer of around 1.1 m. If not, you should get something like 0.981 m.