All Questions
70
questions
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Why the weight vector is perpendicular to the displacement of the object being moved by the tension force in the conical pendulum?
Can someone explain why, in the conical pendulum, the weight vector is perpendicular to the displacement of the object being moved by the tension force in the system? I understand that the tension ...
user282164
1
vote
1
answer
35
views
If a cylinder skids what can we say about the work of friction on it
A cylinder skids on a rough horizontal plane and we know that a frictional force will act on it.
What can we say about the work done by friction?
I believe that the frictional force is forward, the ...
- 1,270
0
votes
0
answers
36
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Work and mechanical energy relationship for a rigid body
For a single particle in a conservative field, I know that the work done by an external non conservative force $W_n=\Delta M$ where $\Delta M$ is the total mechanical energy.
Is the same true for an ...
- 1,270
0
votes
2
answers
122
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Is work done by the normal reaction force when an object is dropped on the ground?
When a perfectly non elastic object (let's say a book) is dropped on the ground, it's kinetic energy from the fall is transformed into heat and sound.
Now, if W = Fs, the work done by the normal ...
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-2
votes
2
answers
46
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Equation for Work required to achieve a certain velocity [closed]
If we are trying to find the work required to get an object moving at velocity $v$, and we start with $w = f\cdot d$, we can then make the following substitutions:
substitute $f$ with ma: $w = m\cdot ...
1
vote
2
answers
50
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Calculating work done vs. calculating final energy [closed]
I'm trying to solve for work after 2 seconds given $v(t)=3t^2$ and mass$=1kg$. There are 2 approaches:
Just calculate kinetic energy after 2 seconds: $E_k=.5*mv^2 = .5 *1 * (3*2^2)^2 = .5* 144 = 72J$
...
0
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3
answers
52
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Does work between 2 bodies depend on their relative speed?
Imagine a car standing on the road. Now the car starts to accelerate.
On the first part, the car accelerates from 0 m/s to 10 m/s.
Some of the fuel was used during this first part. let's call that ...
- 105
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3
answers
334
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Can you define Work as the amount of energy transformed within a system?
Sorry for the relatively long post! Thank you for reading and let me know if there is anything I can clarify/fix.
My textbooks defines Work in the following way:
A measure of the amount of energy ...
- 1,288
0
votes
1
answer
104
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First principle of thermodynamics vs classical mechanics
please I need clarification about the first principle of thermodynamics, it's general statement is:
$$\Delta U + \Delta \text{KE} + \Delta \text{PE}= W + Q .$$
Supposing that: $ΔU = 0$ and $Q = 0$, ...
0
votes
2
answers
615
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Work done by friction over closed path
I am stuck thinking about work done by non-conservative forces. It is path dependent.
Let us consider an example.
A truck starts from rest and a block is kept on it. It accelerates for some time and ...
- 125
0
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1
answer
481
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What came first: the work-energy theorem OR work and energy individually which were later reconciled in a theorem?
What came first: the work-energy theorem OR work and energy individually, which were later related to each other by a theorem?
Were work and kinetic energy defined after arriving at the work-energy ...
0
votes
4
answers
80
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Work done involving two equal objects
I just want to check my understanding. Say I have two equal mass blocks A and B, being pushed together by force $F$ by a distance $D$; ignore friction.
Technically, the total work by $F$ is $FD$, but ...
- 379
8
votes
11
answers
1k
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Is it more work to put more (apparent) effort to get the same outcome?
I was taking my dogs for a walk yesterday evening when this question occurred to me.
The two dogs were pretty enthusiastic about the walk and wanted to run on ahead, so the leads were taut and they ...
- 257
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1
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125
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Force Applied but No Distance Travelled
Suppose I push on a wall with a constant force of 5 N for 10 s. The wall won't move and hence no work will be done on the wall. However, pushing requires energy. How can I find out how much energy I ...
- 251
0
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2
answers
98
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How is energy conserved in terms of "Work"
Basic equation of work is given by $F\cdot s$. When work is done, the energy is stored either in form of potential or kinetic. My question arises when we look at a case of applying $m g$ of force ...
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