3) What is the distance the middle spring is stretched from its equilibrium leng

Question

3)

What is the distance the middle spring is stretched from its equilibrium length?

4)

Now the elevator is moving downward with a velocity of v = -2.4 m/s but accelerating upward at an acceleration of a = 4.3 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

What is the magnitude of the force the upper spring exerts on the upper mass?

5)

What is the distance the lower spring is extended from its unstretched length?

6)

Finally, the elevator is moving downward with a velocity of v = -3 m/s but accelerating downward at an acceleration of a = -2.8 m/s2.

Compare the magnitude of the NET force on each mass:

F1 = F2 = F3

F1 > F2 > F3

F2 > F3 > F1

7)

What is the magnitude of the net force on the middle mass?

A single mass (m1 = 4.2 kg) hangs from a spring in a motionless elevator. The spring constant is k = 254 N/m. 1) What is the distance the spring is stretched from its unstretched length? m Submit 2) Now, three masses (m1 4.2 kg, m2 12.6 kg and m3 - 8.4) hang from three identical springs in a motionless elevator. Now, three masses (m1 4.2 kg, m2 12.6 kg and m3 8.4) hang from three identical springs in a motionless elevator The springs all have the same spring constant given above. What is the magnitude of the force the bottom spring exerts on the lower mass? N Submit

Explanation / Answer

1) kx = mg
254*x = 4.2*9.8
x = 0.162m

2) Force on bottom spring = weight of mass
F = mg = 8.4(9.8) = 82.32 N

3) Distance of middle string = (12.6+8.4)*(9.8)/254 = 0.81m

4) Net force = net mass * g + Net mass* pseudoforce= (4.2+12.6+8.4)*(9.8 + 4.3) = 355.32N

5) Net extension of lowest spring = mass(g+a)/k = 8.4*14.1/254 = 0.466 m

6) Net force on 2 > Net force with no acceleration > Net force with downward acceleration
Correct order = F2 > F1 > F3

7) Magnitude of net force on middle mass = m*a = 12.6*2.8 = 35.28N

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