All Questions
44
questions
1
vote
3
answers
75
views
How much time does it take for an object to fall from space? [closed]
Let's say there's an object of mass $m$ in space, $h$ meters away from the surface of the Earth. $h$ is large enough that $g$ cannot be assumed to be constant. The acceleration varies according to ...
- 117
2
votes
1
answer
267
views
How to calculate the period of non-circular orbits?
How to calculate the period of non-circular orbits?
By conservation of mechanical energy:
$$
E = -\frac{GMm}{r} + \frac{1}{2}\mu \left ( \dot{r}^2 + r^2 \dot{\theta}^2 \right )
$$
By the conservation ...
- 1,525
0
votes
1
answer
44
views
2 Masses on a table confusion - Normal force and weight
Forces up are greater than forces down. However, the masses on the table obviously don't start flying upwards. Am I missing a force here?
- 93
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
1
vote
1
answer
355
views
How does a screw roll down an inclined plane? [closed]
I was thinking about how various objects would slide down on an inclined plane, and I just couldn't figure this problem out.
So let's say I have this screw or cone on its side, on an inclined plane. ...
- 25
0
votes
2
answers
167
views
Angle of projection for the minimum time of flight for a given range
If a projectile has to cover a fixed range under gravity, then what should be the angle of projection for the total time of flight to be minimum?
The initial and final point of the projectile are both ...
- 33
1
vote
1
answer
54
views
Does the force that need to be applied to pull the weight out of a well by string is more at the start?
One way to estimate depth of the well is attaching a weight to a string then throwing it into the well until it touch a hard surface then pulling the string out of the well and evaluate its length.
...
- 277
0
votes
1
answer
648
views
Newton's first law - elevator lift upward and downward force [duplicate]
Why does $F_c$ is equal to $F_g$ and why $F_c$ isn't greater than $F_g$? $F_c$ is moving it upward right, so the force must be greater than gravity to pull it upwards I think.
- 101
0
votes
2
answers
187
views
How could inertial and gravitational mass be even conceptually different?
From https://en.wikipedia.org/wiki/Mass
Although inertial mass, passive gravitational mass and active gravitational mass are conceptually distinct, no experiment has ever unambiguously demonstrated ...
- 105
0
votes
2
answers
174
views
A falling particle on a "roller coaster"
Suppose a particle is sliding down the hill only because of gravity. But then the hill smoothly flattens out and the particle has to pass a circular loop and must not fall off the loop at any instant ...
- 105
0
votes
2
answers
145
views
Why does a system with zero resultant moment turn after temporarily force-tilted?
Say a beam, 3m long from end to end, has a pivot placed at its centre of mass, at half its length i.e. 1.5m. Objects with weight 200N each are placed on both ends of the beam. The system is in ...
- 340
1
vote
2
answers
56
views
Force exerted by blocks on an angled rail
I'm trying to figure out the force exerted on blocks positioned on an angled rail due to gravity. This is the scenario I have (apologies for the poor graphic):
where each block (red square) is ...
- 203
1
vote
0
answers
69
views
Time taken to collide [duplicate]
Two point masses m1 and m2, separated initially by distance d, move towards each other under mutual gravitational force.
Find the time they take to collide?
The main problem I'm having is to solve the ...
0
votes
1
answer
1k
views
Draw the acceleration time graph of a body which thrown vertically upwards at 20 m/s and then comes back down [closed]
I have considered velocity to be positive while going up and negative while coming down. So I think the graph is a straight line a $y=-9.8 m/s^2$ parallel to the x (time) axis because velocity ...
- 220
0
votes
1
answer
240
views
Toppling over of a body
Why does a body topple over only when the perpendicular from its centre of gravity does not pass through its base?
I had read a paragraph on it from a book by Y. Perelman. I did find a half-...
- 496