All Questions
15
questions
-6
votes
0
answers
77
views
Was relativistic mass necessary? [closed]
according to newton if velocity is constant then momentum will stay fix as mass would not change according to conservation of mass and if mass changer the newton will be wrong and if it does not then ...
- 1
1
vote
1
answer
89
views
How do objects with more mass accelerate when pushed downward?
This is kind of a simple question.
I was basing it off Newton's second law, $$F=ma$$
With the same applied force, an object with more mass will accelerate less.
However, what if two objects of unequal ...
- 539
1
vote
4
answers
673
views
How does mass relate to kinetic energy?
I was working on homework and I had to list what kinetic energy depends on. Interestingly, it turns out it's also based on mass, not only speed. Does anyone have an explanation?
- 539
0
votes
1
answer
30
views
Total energy "exertion" raising and lowering a weight
I'm thinking of the example of somebody raising and lowering some kind of weight, say a barbell and what effect the total time takes to perform the whole raising and lowering action would have on the ...
- 191
5
votes
2
answers
850
views
Does kinetic energy rely on the observer mass too since velocity is relative?
There is no 'correct' inertial reference frame according to relativity. Objects are only 'in motion' relative to an arbitrary inertial reference frame. So let us take the following example. A person ...
- 1,009
2
votes
1
answer
43
views
Change of velocity without doing work
Body of mass $1\rm\, kg$ is moving towards left side at velocity of $-2\rm\,m/s$ and is slowing down due to the constant external force until it stops. After that, it's speeding up towards the right ...
- 25
3
votes
1
answer
233
views
Relationship between mass, momentum and kinetic energy
Is there any fundamental reason why (at least mathematically) momentum is the integral of mass wrt velocity and kinetic energy the integral of momentum also wrt velocity? ie
$$p= \int m \ dv = mv$$
$$...
- 133
13
votes
11
answers
4k
views
True or False: energy is conserved in all collisions [closed]
Using introductory physics, how would you answer this question? (I have a disagreement with my instructor and I’m curious to hear your input)
One of us says true because the question doesn’t specify “...
- 139
4
votes
2
answers
632
views
Is the change in Kinetic Energy not equal to the work done when mass changes at some rate?
Here the Rate of change in Kinetic energy is not equal to the the power. Please explain
0
votes
2
answers
76
views
Is there a way to verify that energy of a body is directly proportional to mass, without using the definition?
How would I go about verifying that the energy a body possesses, is directly proportional to its mass to the first degree, without using the definition of work?
How could I show this fact without the ...
3
votes
2
answers
538
views
Does the work-energy theorem assume that the particles of the system have time-independent masses?
$\newcommand{\force}{\mathbf{F}}$
$\newcommand{\velocity}{\mathbf{v}}$
$\newcommand{\position}{\mathbf{r}}$
Here's an incomplete proof of the work-energy theorem:
$$W = \int_1^2\force \cdot d\...
user113773
1
vote
1
answer
346
views
Work-Energy Theorem for Non-Constant Mass
"The net work done on an object is equal to its change in kinetic energy."
Let's say that a rocket is moving upwards while expelling gas and is thus losing mass. (Non-constant mass)
As the object ...
- 395
5
votes
1
answer
1k
views
Mass-energy equivalence and Newton's Second Law of motion
According to Einstein's Mass-energy equivalence,
$ E = mc^2$ OR
$ m = \frac E{c^2}$..... (1)
and According to Newton's Second Law of motion,
$ F = ma$ OR $m = \frac Fa$ ..... (2)
If we compare eq. ...
- 1,387
1
vote
3
answers
10k
views
Relation between Newtons and Kilograms
Work is expressed as $W=Fd$, where the $F$ is in Newton, $d$ is in meters and result $W$ is in Joules.
For example, if I take $1N$ on earth and lift it $1m$ up in the air I have done $1J$ of work.
...
- 133
1
vote
3
answers
166
views
Carrying water on person, or on the frame when bicycling
So, the question is as follows:
What is the difference in work exerted by the rider in the two following scenarios?
a) Rider + bike. Water carried in a holder on the frame
b) Rider + bike. Water ...
- 11