Tagged Questions
0
votes
3answers
94 views
Parachute in vacuum
Consider that the earth is vacuum. Consider a person of weight 100 kg is falling from sky with an parachute . He is free falling at height of 3000 m. When will he reach the ground? What would happen ...
1
vote
2answers
75 views
Gravity mitigated by velocity regardless of mass?
We know that a small object moving fast enough can pass by a planet and escape its gravity. Would this be (theoretically) true in reverse? Meaning a planet moving fast enough past a stationary smaller ...
0
votes
0answers
138 views
What is the pressure in a vertical pipe that has moving fluid through it?
I have a system like this
When the valve is closed, pressure along any point along the thin tube may be found thru pgh. 1. What about when the valve is opened? 2. Does the top of the jar need to be ...
2
votes
2answers
252 views
Lever Mechanics - How to formulate an ideal lever launch
Let's say I have a simple lever as shown below, and the lever is massless and the pivot is frictionless and there is no air resistance. I'm thinking the cradle for the projectile would have to have a ...
0
votes
1answer
63 views
What is the shortest run needed for a “dropped skateboard” rider to reach 160 mph?
I just saw a great clip on the fastest skateboarder to date. He wants to reach 160 mph from a dropped board, but says his speed is limited by the roads currently available. What is the shortest run ...
1
vote
1answer
118 views
Determining Orbital Velocity
Is there any way to determine the orbital velocity of a point around another stationary point, if I don't know the mass of either of the points but know the force that gravity exerts and the distance ...
2
votes
4answers
545 views
How long must escape velocity be maintained?
Escape velocity from Earth's surface is 11.2 Kilometres/second
How long would one need to maintain this escape velocity to actually escape Earth's gravitational pull? Must this 11.2 km/s velocity ...
11
votes
2answers
449 views
What is the terminal velocity for a mobile phone
You may have seen the story of the iPhone which was dropped from perhaps 13,500 feet by a skydiver - it survived.
This made me wonder how to work out the terminal velocity for something like that. ...
1
vote
3answers
1k views
Terminal Velocity
Let Suppose a bullet of 2 gram is falling with the speed of 200km/h.
Now how can we know the time after which it gains it terminal velocity.
Also when it gain its terminal velocity the force of ...
5
votes
2answers
781 views
Escape Velocity of Asteriod 243 Ida
I was reading about this asteroid (apparently, it has a moon, isn't that awesome?) and I started thinking about if I was on this asteroid, and I jumped, would I fall off?
It's been a while since I ...
5
votes
4answers
656 views
A Basic Question about Gravity, Inertia or Momentum or something along those lines
Why is it that if I'm sitting on a seat on a bus or train and its moving quite fast, I am able to throw something in the air and easily catch it? Why is it that I haven't moved 'past' the thing during ...
