All Questions
63
questions
0
votes
2
answers
69
views
Why isn't the moment always included in a free-body diagram?
Now I have seen many times both in my physics book and other books when drawing a free body diagram the moment is not included but the forces are. For example in 2d when a beam is fixed to a wall ...
- 103
0
votes
2
answers
76
views
Misconception About Torque Log cutting example
LOG CUTTING
"Three friends go camping in the forest with their families. They start collecting wood to make a fire. They find a large, branchless log in the forest. One end of the log is very ...
- 73
1
vote
3
answers
99
views
Sign of distance/arm when finding moment/torque
I know that $M=Fd$, but when I have a negative moment, does the sign of the moment matter when I'm calculating for distance? If yes, then what would it mean when distance is negative?
- 11
0
votes
2
answers
405
views
Difference between moment and couple
What is the exact difference between a moment and a couple? In some YouTube channels and books, they say the moment of a force produces a translational as well as rotational motion whereas the concept ...
0
votes
0
answers
33
views
What is the most fundamental reason for introduction of force moment $\vec{M}=\vec{r}\times\vec{F}$? [duplicate]
Force moment is defined as $\vec{M}=\vec{r}\times\vec{F}$ when force is perpendicular to the lever arm.
How do we know that it has to be this way? How do we know it is not $F\cdot r^2$ etc. ?
My ...
- 291
18
votes
3
answers
4k
views
How does a lever arm increase force?
A lever and a fulcrum is able to to multiply the input force to the output force and trade moving distance for increased force. The same happens in automobile transmissions, taking advantage of high ...
- 347
1
vote
3
answers
181
views
Why does moment/torque equal to force multiplied by distance?
moment is equal to force x distance but why is is it so. why is it so that greater the distance less the effort needed? i tried understanding it mathematically but it just went over my head. if any ...
- 11
3
votes
3
answers
1k
views
How do you apply a pure torque?
A pure torque does not have a point of application. For example, in the beam shown below, the reactions are same regardless of the torque placement:
But how do you apply torque in reality?
For ...
- 31
5
votes
1
answer
373
views
If torque is a form of moment, then why is the word 'moment' used for the 'magnetic dipole moment', NiA, for a current-carrying loop?
I thought torque is a form of moment:
If the moment makes the object rotate, we call it torque; otherwise we just use the name moment.
However it seems the electric & magnetic dipole moments are ...
- 410
0
votes
1
answer
208
views
How non-collinear forces balance each other?
In the system of parallel forces , all the forces are non-colinear. So how to they balance each other?.
Here in this case a wooden plank is supported at its end by two supports. All the forces here ...
user329624
-1
votes
1
answer
36
views
Are these two torques identical? [closed]
Hello,
I had this question in a MCQ. According to the solution, these torques are indeed identical but I don't understand how.
I tried to decompose $\overrightarrow{AB}$ into $\overrightarrow{AC} + \...
- 13
3
votes
4
answers
917
views
Why don't simple machines change the amount of energy needed?
Suppose I wanted to tighten a nut and I do so using two spanners of different arm lengths, say of $10 \text{ cm}$ and $20 \text{ cm}$. According to a an online source:
A spanner counts as a simple ...
- 413
0
votes
1
answer
112
views
Why does a long, free-to-move object rotate when I push it from one side?
I was pushing a pencil along a table top when I noticed that it rotates around the other end.
Somewhat like this(The dotted red lines show the final position of the pencil).
The pencil is not pivoted ...
- 1,168
0
votes
0
answers
38
views
Meaning of torque
So, in the diagram, A is the axis of rotation and the net moment from the forces acting there(as shown) is 6Nm.The moment is due to the forces acting in the direction as shown and the moment the ...
- 87
4
votes
2
answers
691
views
Why does a body rotate faster if force is applied away from the pivot?
Why does a body rotate faster if force is applied away from the pivot? I need an intuitive answer to this. Like why does a door rotate slower if I push at it closer to its hinge, or faster if I push ...
- 41