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Jul
31
comment Speed and gravity increase rate
I don't know what you mean by "squaring the gravity". If the factor by which your velocity increases is k, then gravity must increase by k^2 in order for the projectile's range to remain the same. But you don't need to take my word for it - it is simple 7th grade algebra. Plug values into the range equation that I linked to, and solve for g.
Jul
31
comment Speed and gravity increase rate
Yes - see range of a projectile. The range is proportional to v^2/g. So if v' = k*v, then g' = k^2*g if the range is to remain the same.
Jul
31
comment Speed and gravity increase rate
Actually, the scaling factor for speed should be squared when applied to acceleration. For example, 1.0002 * 1.0002 = 1.00040004. You are calculating it as 1.0002 + (1.0002 - 1) = 1.0004. Because your rate is so close to 1, the error from your method is negligible.
Jul
31
comment Speed and gravity increase rate
Why not just speed up time? That will give the appearance of speed increasing, without affecting the distance of jumps.
Jul
31
comment Intro Mechanics: Finding ball speeds after collision
In real collisions, how does nature choose v1? If the collision is completely elastic, then both momentum and kinetic energy are conserved. Those two equations give a unique solution for the final v1 and v2. For a completely inelastic collision, momentum is conserved, but energy is not. However, we have one more piece of info - the masses are stuck together after the collision, so their final velocities are the same. This also gives us a unique solution. So, nature does not have any wiggle room to arbitrarily distribute momentum to one mass or the other - there is only one solution.
Jul
22
comment Is there a general rule for determining the direction of tension force?
@ja72 - Yes, that would be true for a rigid rod. But for homework-type problems, I think you can rule out compression for strings and ropes.
Jul
22
comment Is there a general rule for determining the direction of tension force?
No, the string never pushes the mass.
Jul
22
comment Is there a general rule for determining the direction of tension force?
Try it yourself - tie a string to a block, and grab the other end of the string with your hand. Now, try to use the string to move the block away from your hand. You can't, because the string goes limp. Now try to use the string to move the block towards your hand.
Jul
22
comment Is there a general rule for determining the direction of tension force?
Because the string "pulls" upward - if the force were pointing down, the string would be "pushing" the block.
Jul
22
comment Is there a general rule for determining the direction of tension force?
Here's an easy way to get it right, without worrying about "why": a string can only pull. If you try to push with a string, it will just fold up.
Jul
7
comment Radiation from home heaters
Are you asking whether the radiation from home heating units causes radioactive contamination to build up in your house?
Jul
1
comment Reduction of Earth's Rotation due to increase in humidity
But the atmosphere is not a rigid body. If the atmosphere rotates more slowly than the earth, then the earth's rotation might have to actually increase to conserve angular momentum.
Jun
25
comment How to design a stable table?
You need to define what constraints you want to place on the design. For example, a round tabletop with no leg and no base would be extremely stable. Or, if your base is larger than your tabletop, that will be extremely stable.
Jun
23
comment Good way to compute the force of a hammer blow?
What about pressure? Are you interested in measuring the difference between a hammer with a large striking area vs a hammer with a small area?
Jun
8
comment What is the voltage at every pair of points along a ideal wire that is connecting the two terminals of a battery?
For any segment of idealized wire, consider the voltage anywhere along the segment to be constant. In your game, you will need to separately handle the edge case where a wire shorts out a battery.
Apr
29
comment Does a truck stop faster if the stack on the back of truck is stable or if it moves forward?
This analysis assumes that the moving haystack eventually stops due to friction. If instead the haystack stops due to colliding with the cab of the truck, does that change the answer? Also, would the timing of the collision matter (whether the haystack hits the cab before or after the truck comes to a stop)?
Mar
31
comment In circular motion, with a constant distance, why does the mass of the orbitting object have no effect on its revolution at all?
FYI - the orbiting object's mass does have an effect on the shape of the orbit. For example, if you increased the mass of the moon such that it had the same mass as the earth, the moon would no longer follow a circular path with the earth near its center. Instead, the moon and earth would both orbit around a point halfway between them. See barycentric coordinates.
Feb
16
comment Why does it take a projectile as long to get to its apex as it does to hit the ground?
This is probably the easiest way to explain it to someone in an intro to physics class, as long as you are able to convince the student that v(final) = -1 * v(initial).
Sep
24
comment Did the Big Bang happen at a point?
"The simple answer is that no, the Big Bang did not happen at a point. Instead it happened everywhere in the universe at the same time." By this, do you mean 1) that only the spacial dimensions were collapsed, but time was not, so the Bing Bang occurred at one moment in time, or 2) was all of spacetime collapsed, and the Big Bang occurred everywhere and every time.?
Sep
21
comment If a body is floating in a static fluid, then the volume of the displaced fluid equal to the volume of the inmerse part of the object (proof)
You can't mathematically prove this without first making certain assumptions, and making rigorous mathematical definitions of the physical concepts. Math doesn't know what a "static fluid" is, for example. Another example of where assumptions matter is the fact that not all volumes are additive.