Astronauts in space cannot weigh themselves by standing on a bathroom scale. Ins
ID: 1414318 • Letter: A
Question
Astronauts in space cannot weigh themselves by standing on a bathroom scale. Instead, they determine their mass by oscillating on a large spring. Supppose an astronaut attaches one end of a large spring to her belt and the other end to a hook on the wall of the space capsule. A fellow astronaut then pulls her away from the wall and releases her. The spring's length as a function of time is shown in Figure P14.36. Figure P14.36
(a) What is her mass if the spring constant is 220 N/m? kg (b) What is her speed when the spring's length is 0.80 m? m/s
Explanation / Answer
(a)
k = 220 N/m
From graph it is pretty clear, time period t = 3.0 s
We know,
t = 2**sqrt(m/k)
3.0 = 2**sqrt(m/220)
m = 50.15 Kg
(b)
Amplitue, A = 0.4 m
Total Energy = 1/2*k*A^2
At L = 0.8 m,
Total Energy = 1/2*k*x^2 + 1/2*m*v^2
Using Energy Conservation,
1/2*k*A^2 = 1/2*k*x^2 + 1/2*m*v^2
220 * 0.4^2 = 220 * 0.2^2 + 50.15 * v^2
v = 0.725 m/s
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