All Questions
30
questions
-1
votes
2
answers
111
views
How is work done on an object zero if it’s position is changed with respect to Earth? [closed]
A porter lifts a suitcase weighing 20 KG from the platform and puts it on his head 3.0m above the platform. Calculate the work done by the potter on the suitcase. -Since kinetic energy of the ...
- 153
1
vote
1
answer
1k
views
work done by static friction in different reference frames
Consider the following scenario: A mass of m is kept on a rough inclined surface of angle of inclination $\theta$. The elevator goes up with a constant velocity v and the block does not slide on the ...
- 67
0
votes
1
answer
869
views
Determining whether a force is conservative
From my understanding, most forces that are conservative are of the form
$$\vec F = \hat i F(x)$$
Which means the force is only a function of one variable, which means the work done of the force in ...
- 3,200
0
votes
1
answer
3k
views
Calculating the work done by a particle experiencing a force in polar coordinates
Above is the source of uncertainty I have in understanding the motion of this particular particle. I'm consider (a) here, and here is my thinking:
The particle's motion is hard for me to understand. ...
- 3,200
1
vote
3
answers
594
views
What is the correct way to estimate the work done by a climber?
My teacher gave us a worksheet with word problems and their solutions. It is in German, so I have tried my best to translate it to English:
A 26 year old man climbs Mount Everest (8848 m) in only 8 ...
- 19
0
votes
3
answers
129
views
Do I apply any force towards right when I move an object towards right through air (neglecting air friction)?
I am holding an object in my hand fully extended in air. If I move it towards right , will I have to apply any force in the direction of motion (neglecting air friction)?
In my book they say work ...
- 571
-2
votes
1
answer
99
views
basic question about work exercise [closed]
I am learning independently from Tobochnik's statistical physics text.
He asks a warm up question about work:
A person pushes a block up a frictionless ramp. Is the work positive, negative, or ...
0
votes
1
answer
137
views
How do I calculate the work done on standing an object upright?
So I was trying to figure out how much work someone does when they do a sittup or crunch. I guess to make things simple, I'm imagining a really really thin rod with some uniform mass lying on the ...
- 101
4
votes
2
answers
599
views
Work done changes between reference frames?
(This is not homework; a friend shared with me this puzzler and neither of us can figure it out.) Suppose you are in a plane traveling at velocity $v_1$ relative to the ground. The flight attendent ...
- 43
1
vote
2
answers
1k
views
Work done by reaction forces between objects
Assume that there are no friction forces. If we had a particle sliding down a wedge that is free to move on a smooth surface, why do we ignore the work done by the reaction forces on both the particle ...
- 85
1
vote
2
answers
987
views
Understanding a graph of energy conservation with bounded and unbounded motions?
This graph is from the physics undergraduate text "Classical Mechanics by Douglas Gregory".
Above this graph was the statement:
What I didn't understand is- as stated in the under [*paragraph], won'...
- 75
4
votes
2
answers
488
views
What's wrong with my derivation for the spring constant? [duplicate]
An $8.00\ \mathrm{kg}$ stone at rest on a spring. The spring is compressed $10.0\ \mathrm{cm}$ by the stone. What is the spring constant?
I used conservation of energy to solve this problem. The ...
- 679
-1
votes
1
answer
484
views
Can someone explain the solution (provided) of this conical pendulum work problem [closed]
In the image, it looks like the tangential direction is always 45 degrees away from the string, not 90 degrees. Is it not the circular path that the solution is talking about?
- 111
1
vote
1
answer
2k
views
Solve a problem of work and energy
A man pulling sled of his daughter by a massless rope, climbing a snowy hill whose slope is equal to 15 °. Considering that the mass of the sled is $4Kg$, the girl's $26Kg$ and $\mu _c = 0,25$, ...
- 113
0
votes
4
answers
6k
views
How do you tell what forces do no work?
The total mass of the children and the toboggan is 66 kg. The force the parent exerts is 58 N (18 degrees above the horizontal). What 3 forces/ components do no work on the toboggan?
I said the ...
