Calculating Velocity and Distance for a Coupled Spring-Mass System

In summary, the system consists of two objects, m1 and m2, connected by a light spring of constant s = 100 N/m. When m2 is slowly pushed against m1, the spring is compressed by the amount A = 0.200 m. Upon release, both objects move to the right on a frictionless surface. When m1 reaches equilibrium, m2 loses contact and moves to the right with a velocity of 0.5 m/s. The distance between the objects when the spring is fully stretched for the first time is 0.085m. The decrease in amplitude after m2 breaks free can be attributed to the loss of energy in the system.
  • #1
najd
9
0

Homework Statement


Question statement:
An object of mass m1 = 9.00 kg is in equilibrium while connected to a light spring of constant s = 100 N/m that is fastened to a wall as shown in (figure a):
twoBlocksSpring01.png

A second object, m2 = 7.00 kg, is slowly pushed up against m1, compressing the spring by the amount A = 0.200 m (figure b). The system is then released, and both objects start moving to the right on the frictionless surface.

A- When m1 reaches the equilibrium point, m2 loses contact with m1 (figure c) and moves to the right with speed v. Determine the value of v.
B- How far apart are the objects when the spring is fully stretched for the first time (figure d)?

Homework Equations


T= 0.5mv²
E_tot= 0.5sA²
v_max= Aω

The Attempt at a Solution


Okay, so the amplitude for the coupled system is 0.2 metres. The angular frequency of them both is:
ω= √(s/(m1+m2)) = √(100/(16)) = 2.5/s

The velocity of the second mass would equal the maximum velocity reached by the two objects as they pass the equilibrium point, so:
v_max= Aω= 0.2*2.5 = 0.5m/s

So far so good, now the part which I'm unsure of:
To figure out the distance between them, first I calculated how far the spring will get stretched after m2 loses contact with m1.
1- I calculated T for m1:
T1= 0.5m1v² = 0.5*9*(0.5)^2= 1.125J

2- I used conservation of energy to calculate A:
E1_tot= T1 and so,
A= √(2T/s) = √(2*1.125/100) = 0.15m
[This turned out to be less than 0.2m, is that even logical? I mean, the amplitude decreased after m2 broke free. I imagine it should increase.. even though it looks smaller in the figure.]

3- I calculated the time needed for m1 to reach that position:
τ= 2∏/ω1 = 2∏√(m1/s) = 2∏√(9/100) = 1.88s for a whole cycle.
And so, the time for a quarter of a cycle would be:
1.88/4 = 0.47s

4- I calculated the distance traveled by m2:
d= vt = 0.5*0.47 = 0.235m

5- I subtracted the amplitude of m1 from the distance traveled by m2 to obtain D.
D= 0.235-0.15 = 0.085m.

Anything wrong with what I did?
 
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  • #2
najd said:
[This turned out to be less than 0.2m, is that even logical? I mean, the amplitude decreased after m2 broke free. I imagine it should increase.. even though it looks smaller in the figure.]

I assume the amplitude decreased because the system lost part of its energy as m2 broke free, and so, it would make sense.. correct me if I'm wrong, please.
 

What is "Spring Pushing Two Masses"?

"Spring Pushing Two Masses" is a physical system in which two masses are connected by a spring and are subject to external forces.

What is Hooke's Law and how does it relate to "Spring Pushing Two Masses"?

Hooke's Law states that the force exerted by a spring is directly proportional to its displacement from its equilibrium position. In "Spring Pushing Two Masses", this means that the force exerted by the spring on each mass is dependent on how far they are stretched or compressed from their resting position.

What factors affect the motion of "Spring Pushing Two Masses"?

The motion of "Spring Pushing Two Masses" is affected by several factors, including the masses of the objects, the stiffness of the spring, the initial displacement of the masses, the external forces acting on the system, and the friction or resistance present in the system.

What is the equilibrium position in "Spring Pushing Two Masses" and how does it impact the system?

The equilibrium position in "Spring Pushing Two Masses" is the point at which the forces on the two masses are balanced and there is no net force acting on the system. When the masses are at this position, they will remain at rest unless disturbed by an external force.

How can "Spring Pushing Two Masses" be used in real-world applications?

"Spring Pushing Two Masses" has many practical applications, including in shock absorbers, car suspensions, and door closers. It is also used in engineering and physics experiments to study the principles of motion and forces.

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