All Questions
25 questions
0
votes
1
answer
64
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Aerostatic force experienced by object due to air
This is an undergrad physics problem, which puzzled me because of the little background provided; see also the comment below by @RC_23.
Problem.
Compute the force exercised by the air to an object ...
- 103
0
votes
1
answer
76
views
How do you find the distance between a massive object and its certain gravitational force?
Okay so I know I might've not phrased the question very well so I will give an example to try to make sense of it:
Say we have the moon and a place in space where the moon's gravitational force is 1,...
- 43
1
vote
1
answer
67
views
What will be the tension force in this case?
Suppose I have a block of mass $2\, {\rm kg}$ sitting on my table. Then I connect a string to it and pull it vertically upwards. The resultant acceleration is vertically upwards: $2.2\, {\rm ms}^{-2}$....
- 1,028
2
votes
3
answers
377
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
2
answers
306
views
Time taken for a body to crash into the sun [closed]
A small body starts from rest towards the Sun from the position of Earth, find the total time it takes for the body to crash into the Sun (assume Sun is a point object and no other forces act on the ...
- 3
4
votes
2
answers
171
views
Two bubbles attract or repel?
I have this weird thought that bothers me, but unfortunately, I know little physics and I thought I can get help to mentally settle it.
Here we go:
Let's say you have infinite sand or at least a vast ...
- 141
0
votes
4
answers
83
views
Slope without friction - circular motion problem
An object of mass $m$ travels down a slope on earth without friction. At the bottom of the slope, what is the force exerted on the object by the ground?
My textbook says that this force cannot equal $...
- 1,235
0
votes
0
answers
181
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Attractive central force problem with impact parameter
Let $m$ be a mass subjected to a central force:
$$\vec{F}(r) = -\frac{k \mu}{r^3} \vec{u_r} $$
Where $k$ is a positive constant and $\mu$ is the reduced mass of the system with the centre of forces ...
- 221
0
votes
1
answer
1k
views
Question about inclined planes and constant velocity [closed]
I apologize that this is such a simple question, but I am a beginning physics student trying to learn more in his spare time. I can't find a satisfactory answer anywhere since most inclined plane ...
- 1
2
votes
1
answer
52
views
Strength of tides induced by the Earth on the Moon to Moon on the Earth calculation [closed]
In my astrophysics problem sheet I have to compare the strength of tides induced by the Earth on the Moon to that induced by the Moon
on the Earth.
This is my attempt:
$$F_\text{grav}=\frac{GM_\text{...
- 1,545
0
votes
2
answers
85
views
A bullet fired at a pendulum
I am taking a first year undergrad physics class (waves & modern physics), and the answer my book gives to the question bellow has left me a bit confused.
Here is the question (excuse me if it’s ...
- 55
1
vote
2
answers
867
views
Vertical Circular Motion and Tension
I stumbled across this problem on a physics test, and I'm convinced the correct answer (C) is wrong.
The explanation simply states that all the signs are correct, and in circular motion, inward ...
- 134
0
votes
2
answers
965
views
Weight distribution's effect on riding uphill
Two different chains of cars (attached to each in a row) are driving uphill (Only the first car is motorized):
The first chain consists of 3 cars, each 4000 kg.
The second chain consists of 3 cars, ...
0
votes
2
answers
576
views
Sum of normal forces
For the red block to not go through the black block the black block needs to push the red block with equal force(normal force) or else it will go through the black block, but where is the normal force?...
- 13
1
vote
3
answers
161
views
Is there a difference in the Helicopter power needed to stay on different altitudes?
I heard that what can make a helicopter go higher is the presence of "Air" to power its engine.
Let's assume that the amount air would be exactly the same at different altitudes, would the power ...
- 111
18
votes
3
answers
5k
views
Gravitational force when standing on an infinite disc
If a person were to stand on a flat disc of thickness 1 meter but infinite diameter, would they experience finite or infinite downward force?
There is an infinite amount of mass, all of which ...
user55611
1
vote
2
answers
328
views
tension and friction
I had an exercise like the image, where block A is pulled by a force F, there is that rope(tension) attached to the block B and the wall, and there is friction between A and B, and A and the ground, ...
- 365
3
votes
4
answers
417
views
What are the accelerations of blocks? [closed]
I've talked with 2 teachers about this situation:
one teacher said he was completely sure that B have twice the acceleration of A, the other said he was completely sure they have same acceleration. ...
- 365
0
votes
1
answer
451
views
How fast could Earth spin and sustain life? [closed]
When dinosaurs roamed the Earth was the Earth rotating faster creating less gravity to allow for their size? How fast could have the Earth spin and be slowed down by an asteroid to the current ...
- 1
1
vote
2
answers
861
views
What depth should water be filled to in a cylinder flask to make it the most stable
As said in title, a cylinder flask with a mass of 100g and radius of 3 has a center of balence 10cm above the base. Assuming negligible wall thickness, to what depth should water be added to this ...
- 11
0
votes
2
answers
2k
views
Force acting on center of mass
Pictured above is a biker (traveling in a curve) whose center of mass has two forces acting on it.
These two forces - a horizontal centrifugal force F(centripetal)* and a vertical gravitational force ...
- 3
0
votes
1
answer
435
views
A change in the mass of the moon [closed]
Would a change in the mass or radius of the moon have any effect on its speed?
When asked this question in an assignment, I stated that it did not. My reasoning being that a change in the mass or ...
- 33
2
votes
3
answers
50k
views
Vertical and horizontal components of forces and vectors
I'm getting a bit confused when finding components of vectors and forces.
In problems for vectors, I've always known that if you want to get the components of a vector, you would use the following:
...
- 185
2
votes
2
answers
596
views
Raising a toolbox with a rope
Suppose you use a rope to hoist a box of tools vertically at constant speed v. The rope exerts a constant upward force of magnitude F_up on the box, and gravity exerts a constant downward force (the ...
- 201
2
votes
1
answer
3k
views
Calculating the force of a mass bearing down on an object
I need to calculate the force of a weight bearing down on a smaller object, constraining it from expansion.
The weight bearing down has a much bigger surface area than the smaller object.
I know the ...
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