All Questions
126
questions
-1
votes
1
answer
19
views
Strain energy stored in a bungee cord pulled at its midpoint [closed]
A bungee cord that behaves elastically has an unstressed length $L=.76$ m and a stiffness $k=140$ N/m. The cord is attached to two pegs, distance $b=.38$ m apart, and pulled at its midpoint by a force ...
0
votes
1
answer
37
views
What are the points to note in a spring+block system? [closed]
This is the solution to a question related to spring+block system, and I have some doubts regarding the concept behind this question
The solution reads
The velocity of the block increases till the ...
- 91
0
votes
0
answers
27
views
About reference of potential energy
I have an exercise with a pendulum starting at horizontal position, then we give it a velocity of 5m/s pointing down, $z=0$ at this horizontal position and potential energy = 0. This confuses me ...
5
votes
3
answers
2k
views
If a car is *accelerating* uphill, does it *gain* kinetic energy?
I had an exam yesterday on physics (9th Grade), there was a question that confused me a lot. It said: "If a Gas Car is accelerating uphill, what happens to its G.P.E and K.E?"
A: It loses ...
- 61
1
vote
2
answers
219
views
Lagrangian function of a mass-spring-system with deflections in 2D [closed]
I’m looking for the lagrangian function of the following problem (as seen in the picture). We have a mass connected to two springs. We can deglect the mass in two dimensions.
My main problems are:
...
- 11
0
votes
1
answer
93
views
Potential energy involving both elastic and gravity
A block of mass $m$ is placed against an ideal spring as shown. Initially the spring (of force constant $k$) is compressed by a distance $s$. The block is then released and slides a distance d up the $...
0
votes
2
answers
68
views
Minimum initial velocity to avoid collision [closed]
I'm having problem with the solution of this question:
Two material points with mass $m$ move along a horizontal axis subjected only to Newton's gravitational force law. At the instant $t_0=0$, one ...
- 237
4
votes
3
answers
250
views
Why is my answer for height negative?
Question is simple. A ball is thrown upwards with initial velocity $v_0$. How high does it go up?
Assume down is negative and up is positive and no air resistance.
KE at bottom = PE at the top:
$\...
- 109
1
vote
1
answer
26
views
Right displacement in spring potential energy [closed]
I have a doubt in general, the above problem is an example.
Here , the elastic string can be treated as a spring and we know the potential energy of a spring is $\frac{1}{2} k (x_f-x_i)^2$
So , ...
- 11
0
votes
3
answers
67
views
How do velocities become equal when potential energy is maximum? [closed]
I was given this diagram and asked to find the maximum potential energy during the subsequent motion if one of the blocks is projected with a kinetic energy K initially.
So I did reach upon the answer ...
- 23
-1
votes
1
answer
135
views
From my reference frame, why does the Earth need a huge kinetic energy [$0.5M_E(11200)^2=3.75*10^{32}$ joules] to escape me? [closed]
I wake up screaming into the void, when I see the Earth almost touching me but going away from me at 11.2 $km/s$.
I don't remember what happened before I woke up. I faintly recollect being cannoned up ...
- 1,421
5
votes
1
answer
114
views
Insecurity about introductory classical mechanics [closed]
This is a problem I encountered, but not a homework assignment, I'm not only just looking for solutions here... This is my first time encountering questions like this, I'm sure you remember the first ...
- 287
0
votes
2
answers
50
views
Orientation of gravity force in energy [closed]
My apologies in advance if this is a stupid question.
A 0.20 kg rocket in a fireworks display is launched from rest and follows an erratic flight path
to reach the point P, which is 29 meters above ...
- 179
0
votes
2
answers
195
views
Marble "rolling" on the graph of a function
Consider a guide for marbles whose profile locally coincides with a function $f(x)$, for example
$f (x) = - \frac{1}{2} x ^ 4 + x ^ 3 + x ^ 2-2x + 1.$
Suppose that the reference system is chosen in ...
- 11
0
votes
1
answer
382
views
A block starts from rest at the top frictionless slide at a height $h_1$ above the ground and leaves the slide perfectly horizontally
A block starts from rest at the top of a frictionless slide at a height h1 above the ground. The block leaves the side moving perfectly horizontally at a height h2 above the ground. The block ...
