All Questions
33
questions
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2
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83
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Total Energy to Total Momentum
Suppose I have two particles with different masses and velocities. The momentums are as follows:
$$\mathbf{p}_1 = m_1 \mathbf{v_1} $$
$$\mathbf{p}_2 = m_2 \mathbf{v_2}$$
The total momentum is:
$$\...
- 2,599
4
votes
7
answers
492
views
Where does this conservation of momentum gedankenexperiment go wrong?
Inspired by this question.
Let's say I'm standing on a frictionless ice rink right next to a $1kg$ block. I push the block with $1N$ force for a distance of $1m$. I do $1J$ of work, obviously. By ...
- 21.4k
0
votes
1
answer
65
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What is the reason why we cant apply work-energy theorem during the period of motion when the bigger block is at rest? [closed]
Question: *A big block of mass $2m$ is placed near a wall in such way that only its left side touches the vertical wall. Now a ball of mass $m$ is released from top (near to the side of the wall) of a ...
1
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1
answer
71
views
Why work done by internal force is changing with frame in this case?
I read somewhere that
work done by internal forces is independent of frame of reference
but suppose a man of mass $m$ is standing on a stationary smooth cart of mass $2m$, placed on a smooth surface....
- 379
0
votes
1
answer
54
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What force does work on the block in following question? [closed]
In Figure 1, I have shown the initial position of a block of mass $M$ with circular track and at start of the track is a cylinder of mass $m$ . Now initially the system is at rest. All surfaces are ...
- 483
2
votes
5
answers
4k
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What happens to Kinetic Energy in Perfectly Inelastic Collision?
I’m going over a chapter on linear momentum in my physics course right now and am somewhat puzzled with what happens with some of the kinetic energy that is lost in a perfectly inelastic collision.
...
- 375
1
vote
2
answers
640
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Confusion with Impulse and Work [duplicate]
I get Momentum and Impulse as well as Work and energy but struggle when it comes to connecting the two ideas. I understand that an objects KE can change without its momentum changing, Like in a ...
- 139
1
vote
3
answers
81
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Confusion regarding work
Suppose that two forces with corresponding value are acting on the same object with mass m. Force A travels through a distance of 1 m, whereas the other a distance of 3 m. The work done by force B is ...
- 13
0
votes
2
answers
79
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If net $F=0$ on a system then KE of the system may change due to internal forces or due to internal work done
While explaining Centre of Mass, my teacher told this exact statement that "If net $F=0$ on a system then KE of the system may change due to internal forces or due to internal work done."
...
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-1
votes
2
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73
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Is it possible to change the momentum of a system without actually doing any work on the system?
Consider a rigid wall somewhere in free space. Now imagine two balls of the same mass and same speed headed towards the wall from two opposite directions. Now they go on to hit the wall and rebound ...
- 97
1
vote
2
answers
373
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Influence of object mass on impact force
Suppose I am throwing horizzontally a ball with mass "m" against a wall (whose mass and stiffness can be assumed to be infinite).
I accelerate the ball with a constant force "F" ...
- 719
0
votes
2
answers
123
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Conservation of momentum and work
Consider the following scenario:
I am alone in space with a ball. I threw the ball at a certain speed such that i am propelled backwards (like a rocket is) as to conserve momentum. Now, since my ...
- 43
9
votes
5
answers
1k
views
Is the average force calculated from $F(x)$ the same as that calculated from $F(t)$?
Say a force is doing work on an object in one dimension. I could calculate the average force over the distance with
$$\frac{1}{\Delta{x}}\int_{x_1}^{x_2} F(x) \text dx$$
If I also formulated force ...
- 195
2
votes
4
answers
133
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How can kinetic energy not be conserved if momentum is conserved in a system? [closed]
If there is no net force on a system, energy is conserved.
Then, how can there be work at all since work is the integral of dot product of force and $dr$ ? If force is $0$, wouldn't work ...
- 33
2
votes
4
answers
3k
views
Why is work defined as $W=Fd$?
I am trying to understand what work really means in physics. I seem to be missing the conceptual link. Every resource says that $W=Fd$ but that does not make sense to me.
If, say, an elastic object ...
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