All Questions
83
questions
0
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1
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80
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Where am I wrong in proving that force perpendicular to motion increases speed and kinetic energy? [closed]
Lets think of a helicopter flying at some height $h$. It throws a food packet to a person on the ground from air. Let's neglect the air drag.
The food packet is thrown only with some velocity $v_x$ in ...
- 85
2
votes
2
answers
111
views
Why do higher objects have a greater force?
We did an experiment in class today using a spring scale, a plastic bag, and a variety of other objects. Essentially, we attached the bag to the spring scale and measured the force, in newtons, of ...
- 539
1
vote
1
answer
29
views
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
votes
3
answers
426
views
How does gravitational potential energy work in a very large distance?
Consider a thought experiment (that I made when I was in high school) involving a universe with only two objects: a massive planet and a small asteroid. Initially, they are millions of light-years ...
- 109
0
votes
3
answers
113
views
How does gravity do work to a horizontal projectile?
Suppose a ball is moving in a horizontal projection with some velocity $u_0$ in the positive $x$ direction. Here we see that although gravity is perpendicular to the velocity vector, it changes the ...
- 11
0
votes
0
answers
393
views
Relationship between height and mass?
Objects with different masses are placeed on the horizontal surface of a table. The objects are then raised to different heights above the tabel. The gain in gravitational potential energy of each ...
1
vote
1
answer
336
views
How to calculate the energy in a hyperbolic orbit?
I'm recently reading a book about rocket science which involved orbital mechanics. I know that in an elliptical orbit, the energy $ E=-\frac{GMm}{2a}$, and therefore can get the vis-viva equation: $ ...
- 11
12
votes
5
answers
2k
views
Why is cycling easier while standing on the pedals?
On high slopes and rugged terrains, riding a bicycle while standing on the pedals is easier. Even though I cannot physically define what is "easy"; since it is a feeling that my body ...
- 12.5k
-1
votes
1
answer
283
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Increase in the internal energy of the block-surface system due to friction [closed]
I found this question:
https://plainmath.net/force-motion-and-energy/13968-block-dragged-horizontal-surface-acting-degree-horizontal-displaced
and I'm trying to understand why he used this formula to ...
0
votes
2
answers
55
views
Work done by gravity confusion
Say we had an object at height $h$ in a gravitational field, and of mass $m$, its GPE would equal $mgh$, now say we dropped it and it fell a distance of $h$, the work done on the object would be equal ...
- 195
0
votes
1
answer
48
views
$N$-body simulation: total energy is conserved, but what about the energy of a specific particle? [closed]
It is clear that the total energy in a full gravitating $N$-body simulation should be conserved, but what about the energy of an individual particle? Is this not conserved, since the potential is ...
0
votes
2
answers
21
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Constant energy in universe and spacecraft accelerating [duplicate]
Given that the energy in the universe is constant, how is it that spacecrafts traveling far distances sometimes get a boost by falling into the gravitational field of a planet? Acceleration caused by ...
- 107
-1
votes
2
answers
212
views
Why does GPE convert to kinetic energy? [closed]
What is it about GPE that makes it transfer to kinetic energy, why does it do this? What is GPE?
0
votes
2
answers
86
views
Is the topic of gravitational potential energy convoluted and unnecesary? [closed]
If we throw an object upwards from the surface of the Earth, we do some work on it to give it kinetic energy. Now as it travels up, Gravity of the Earth does negative work on it till it loses all the ...
0
votes
1
answer
54
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Why Gravitational Potential is same In Both these cases?
We usually choose Reference point as Infinity which is Linear to the Points
and by this way we gat work done as both force and displacement are in the same direction as well as in the same line which ...
- 121