Forced harmonic motion-Help Watch

Omar.Q
Badges: 1
Rep:
?
#1
Report Thread starter 4 years ago
#1
How do get the equation in the question?, dont know how to relate (u) into it. help
Name:  Forced harmonic motion.jpg
Views: 65
Size:  222.9 KB
0
reply
atsruser
Badges: 11
Rep:
?
#2
Report 4 years ago
#2
(Original post by Omar.Q)
How do get the equation in the question?, dont know how to relate (u) into it. help
1. At time = 0, the nett force on the particle F=0 since it is just about to move. This is because the extension in the spring is just balancing the (limiting) frictional force due to the rough table.

2. Thereafter, the end of the spring A moves further away from the particle, and hence the extension increases so that the force due to the spring is greater than the limiting frictional force.

3. At time = t, the extension in the spring has changed, since end A, which is moving with speed u has moved a certain distance away from the particle. What is this distance? (Hint: SUVAT)

4. However, at time = t, we are told that the particle has moved distance x from its original position, clearly towards A.

So

a) what is the nett change in extension e_t of the particle at time t?
b) what is the nett increase in force due to the spring, in terms of e_t?
c) what is the total force felt by the particle, at time = t?
d) what equation do you get when you apply Newton II using the info above?
0
reply
Omar.Q
Badges: 1
Rep:
?
#3
Report Thread starter 4 years ago
#3
(Original post by atsruser)
1. At time = 0, the nett force on the particle F=0 since it is just about to move. This is because the extension in the spring is just balancing the (limiting) frictional force due to the rough table.

2. Thereafter, the end of the spring A moves further away from the particle, and hence the extension increases so that the force due to the spring is greater than the limiting frictional force.

3. At time = t, the extension in the spring has changed, since end A, which is moving with speed u has moved a certain distance away from the particle. What is this distance? (Hint: SUVAT)

4. However, at time = t, we are told that the particle has moved distance x from its original position, clearly towards A.

So

a) what is the nett change in extension e_t of the particle at time t?
b) what is the nett increase in force due to the spring, in terms of e_t?
c) what is the total force felt by the particle, at time = t?
d) what equation do you get when you apply Newton II using the info above?
for extension when tension equals friction i got µg/n^2, for newtons second law, im confused how theres acceleration if theres a constant speed, also can you show me how to answer the questions please
0
reply
atsruser
Badges: 11
Rep:
?
#4
Report 4 years ago
#4
(Original post by Omar.Q)
for extension when tension equals friction i got µg/n^2,
That looks right.

for newtons second law, im confused how theres acceleration if theres a constant speed,
End A of the spring is being moved with constant speed - something is pulling it. However, the mass on end B is accelerating towards end A, since the spring is being stretched. It will accelerate until the extension of the spring once again is small enough to produce exactly the frictional force due to the floor.

also can you show me how to answer the questions please
If you figure out the answers yourself, you'll learn how to solve the problem. I've already provided all of the hints that you should need.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of East Anglia
    All Departments Open 13:00-17:00. Find out more about our diverse range of subject areas and career progression in the Arts & Humanities, Social Sciences, Medicine & Health Sciences, and the Sciences. Postgraduate
    Wed, 30 Jan '19
  • Aston University
    Postgraduate Open Day Postgraduate
    Wed, 30 Jan '19
  • Solent University
    Careers in maritime Undergraduate
    Sat, 2 Feb '19

Brexit: Given the chance now, would you vote leave or remain?

Remain (863)
80.28%
Leave (212)
19.72%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise