All Questions
16
questions
1
vote
1
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29
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Describe the decrease in potential energy if two forces are acting on it one conservative which is greater than other applied by us in opposite dirn [closed]
So imagine this situation.
An object is experiencing two forces, one due to gravity in downward direction and other applied by us in upward direction such that our force is less than gravitational ...
- 13
1
vote
1
answer
32
views
Work done on a body and work done by the body
I want to know that, if we suppose that, if a ball is falling freely then work would be done on the ball by gravity so energy would be given to the ball? and when the ball rebounds after striking the ...
- 79
0
votes
2
answers
129
views
In two particle system why can't we calculate the gravitational potential energy of each mass separately and find the net potential energy?
In a two particle system, suppose both are moving by their internal gravitational force, and hence the potential energies of the system is changing. Since both are acted upon by the conservative ...
- 121
2
votes
3
answers
334
views
How much work is done to maintain vertical position (hovering) of a drone? [closed]
Ignoring all losses in the efficiency of the means to lift the drone, this would reduce down to resolving the key elements of the equation involving a) the acceleration of gravity and 2) the time, and ...
- 129
0
votes
0
answers
68
views
What is the net work done on two different systems?
Assume that we applied a force on an object so it moves at a constant speed upward, and we defined our system as the object only.
I was taught in my physics class that if we want to calculate the ...
- 31
0
votes
1
answer
52
views
How does work done to move an object scale with more/less gravity?
First let me say that Physics is not my area of expertise and my knowledge from school is pretty rusty, so I apologize in advance if I am asking a totally stupid thing or I have a mismatched ...
- 23
-1
votes
2
answers
369
views
How can a system of Atwood machine lose gravitational potential energy?
The heavier block in an Atwood machine has a mass twice that of the lighter one. The tension in the string is 16.0 N when the system is set into motion. Find the decrease in the gravitational ...
- 137
0
votes
1
answer
37
views
Difference in work done for different directions of motion [closed]
If I am lifting a weight, i.e, a rectangular object of 200kgs from one end off the ground(around 3 inches above the ground) having a dimension of 48 inches by 30 inches. How much weight am I lifting ...
- 111
0
votes
1
answer
23
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Work by gravity for a generic movement
When my book explains the work by gravity it doesn't explain why it passes from the shift (edit: the blue line in the picture) to the ray in this integral
Of course, I understand that the work ...
- 13
2
votes
5
answers
44k
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when an object is lifted (at a constant velocity) shouldn't the work done on the object be zero? [duplicate]
When I lift an object from the ground (at a constant velocity) I'm applying force on the object equal to its weight and the earth is also pulling it downwards with equal amounts of force. So if the ...
- 101
2
votes
4
answers
542
views
If velocity is constant, how can $p = F\cdot v$ be non zero?
If an airplane of mass $m$ is flying at a constant speed $v$, the power of the airplane is
$$P = m\cdot v\cdot g
$$
where $g$ is the acceleration of gravity and therefore:
$$
F = m\cdot g,
$$
but, ...
- 101
3
votes
0
answers
2k
views
How much work can a single grain of rice do? [closed]
I found a website saying a grain of rice contains 1/10 kcal.
I'm not a physicist and haven't done maths for a long time. But here's what I came up with:
E = m * g * h
One small calorie equals 4....
- 139
0
votes
2
answers
433
views
Why is the potential energy for a body raised up by a height negative?
I tried deriving the potential energy of a body when raised at a height $h$ above the earths surface, using the formula:
$$PE = -W_\text{conservative}$$
where $W_\text{conservative}$ is the work ...
0
votes
1
answer
174
views
Gravitational work
As far as I know gravitational work is independent from the path of the object, and I have an object that goes up on a inclined plane to a certain height, and than, after the object reaches the edge ...
- 11
1
vote
3
answers
2k
views
Work done by gravity on a ball & the ball on earth
I have studied today that if a ball was to fall a certain height, then the work done by gravity on the ball would equal the work done by the ball's equal and opposite gravitational pull.
By $W=Fd$, ...
- 111