Sliding block with motion restricted by spring

AI Thread Summary
A block of mass 2 kg slides on a frictionless track attached to a spring with a relaxed length of 4 m and a spring constant of 8 N/m. The spring is extended by 1.65 m when the block is pulled to one side, storing 10.89 J of potential energy. Upon release, the block reaches a maximum speed of 3.3 m/sec. The discussion seeks assistance with calculating how far the block travels after being given an initial speed equal to its maximum speed and determining its acceleration at the point of maximum spring stretch. The user expresses frustration over the complexity of the problem and uncertainty about their calculations.
itsalana
Messages
1
Reaction score
0
Restricted Block on Spring
A block of mass m = 2 kg slides back and forth on a frictionless horizontal track. It is attached to a spring with a relaxed length of L = 4 m and a spring constant k = 8 N/m. The spring is initially vertical, which is its the relaxed postion but then the block is pulled d = 4 m to one side.

Screen Shot 2014-03-06 at 2.41.47 PM.png


1. By what length is the spring extended?
1.65 M OK

2. What is the potential energy stored in the spring?
10.89 J OK

3. The block is released. What is the maximum speed it attains?
3.3 m/sec OK


I need help with 4 and 5. If someone could just help me, PLEASE?!

4. Let's change the problem a bit. When the spring is vertical (hence, unstretched), the block is given an initial speed equal to 1 times the speed found in part (c). How far from the initial point does the block go along the floor before stopping?

5. What is the magnitude of the acceleration of the block at this point (when the spring is stretched farthest)?



The Attempt at a Solution


4. So I thought that since on relaxed position, then the only work is on spring
so 1/2 k x^2 with x as 4.
When I got that number, I set that equal to 1/2k (x2-x1).
so I got a -2.72 then I subtracted that to L so 4-2.72. Then i used pythagorean and find d.
It's wrong.

I guess 3.99 and I got it right, but I have no idea how I got 3.99. It was literally a number i just typed in.

5. So for 5, with 3.99 and having no idea how I got 3.99 I don't even know where to start.

Please, if anyone could help me!
I have been working on this question for a total of 4 hours.
Please!
 
Last edited by a moderator:
Physics news on Phys.org
If the block is given an initial speed at equilibrium, will it ever have a speed greater than the initial speed?
 
Please Note: The thread title has been changed to make it descriptive of the thread content.
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top