Then, if that is true, in baseball, what is the difference between a slow ball and a fast ball?

can't say i've ever heard anybody refer to a pitch called a 'slow ball' in baseball, jeannie. but a slow curve thrown at the same time as a fastball will hit the ground long before the fastball does if both get by the catcher.

Well I've heard of a fast ball so I just assumed that there was probably a slow ball.

So what is the difference between a fast ball and a regular ball?

No. The time it takes to hit the ground is the same whether the bullet is zero ft/sec horizontal or 4000 ft/sec horizontal. The horizontal distance is dependent on the horizontal velocity and the distance will depend upon how long it takes a bullet to fall to the ground.

For example (assume no air resistance), You fire a gun at exactly the same time as you drop a bullet from the same height. It takes one second for the falling bullet to hit the ground. The fired bullet is traveling at 4000 ft/second. The bullet hits the ground one second after being fired (same as the other) but 4000 feet away.

In reality the fired bullet would not travel 4000 feet because it would be slowing down the whole time from air friction. It doesn't matter the weight (mass) of the bullets or the velocity, they still hit the ground at the same time. If you look at the formula for gravity, velocity is not a variable.

i'll bow to your reply to this one moe.

Throwing and Dropping Objects

Date: 11/26/2002 at 23:24:14
From: Amanda Evans
Subject: Math

I have tried asking my teachers this question, but they say I am too
young to understand the answer. I have even asked my parents, but they
give me the same answer. I cannot find this answer anywhere. My
question is very simple.

Why, when you throw something in one direction and drop something at
the same time, do they land on the ground at the same time?

Also, when you throw something in the air, does it come down at the
same pace as it went up?

Thank you for taking the time to read this.

Date: 11/27/2002 at 10:59:15
From: Doctor Ian
Subject: Re: Math

Hi Amanda,

It's a good question! A lot of people only understand this kind of
thing in terms of equations using variables, so they can't explain it
to someone who hasn't studied algebra yet. But let's see if we can
skip the equations and just talk about the ideas, okay?

The answer to your first question assumes that you throw the item in a
horizontal direction. Viewed from the side, the situation would look
sort of like this:

throw
' ' ----->
' '
d ' '
r ' '
o ' '
p ' '
'
' '
' '

If you throw the item in an upward direction, it will take more time
to hit the ground. If you throw it in a downward direction, it will
take less time. (By the end of this, you should understand why.)

It might be easier to see what's going on if we imagine that you and I
are going to have an odd kind of race. We're both going to start at
the same point, and you're going to move south, following a simple
rule: In the first second, you'll take one step; then in the second
second you'll take two steps; then three steps; then four steps; and
so on:

X
| 1 step per second
---
| 2 steps per second
|
---
| 3 steps per second
|
|
---
| 4 steps per second
|
|
|
---

What this means is that as time goes by, you'll be moving faster and
faster. It's like what a car does as it pulls away from a stop sign.
In the first second, it goes 5 feet; then 15 feet in the next second;
then 35 feet in the next second; and so on. This kind of motion is
called 'acceleration', which is just a fancy word for 'changing
speed'. We say that the car 'accelerates' from a speed of zero to
whatever its final speed (say, 45 miles per hour) turns out to be.

(When the car comes to the next stop sign, the speed decreases, and
sometimes we call that 'deceleration', but in both cases, it's really
an acceleration, that is, a change in speed.)

So in our race, you're accelerating toward the south.

While you're heading directly south, I'm going to do something a
little sillier. In the first second, I'll take one step east and one
step south; then I'll take another step east and two steps south;
then one and three; and so on. What would that look like?

X---
| |
1 1---
| |
| |
2 2---
| |
| |
| |
3 3---
| |
| |
| |
| |
4 4

So at the end of 4 seconds, I've moved to the east at a constant rate,
and you haven't; but we've _both_ moved toward the south, and with
the same acceleration.

If we change 'south' and 'east' to 'down' and 'over', this is more or
less what happens when you drop one thing and throw a second thing in
a horizontal direction.

Note that it doesn't matter how fast I move to the side. If I move
three steps east during each second, it looks like this:

X---------
| |
1 1---------
| |
| |
2 2---------
| |
| |
| |
3 3---------
| |
| |
| |
| |
4 4

So the curve that I make - or the curve made by the thing you throw -
has a flatter shape, but it doesn't affect the southward/downward
movement.

Let's think about the car again. What makes it accelerate? In short,
we get the engine to burn fuel to produce energy, and we use the
energy to apply a force to the car - just as if we got out of the car
and started pushing on it from behind. (The engine can generate a lot
more force than a few people, though!) So whenever we apply a force to
something, it accelerates. The more force we apply, the more
acceleration we get. (Sometimes in car commercials, you'll hear that a
car can go 'from zero to 60 in ___ seconds'. If a car can accelerate
quickly, it means that the engine can generate a lot of force.)

When you drop a ball, it accelerates too. What makes it accelerate?
As we currently understand it, everything in the universe exerts a
little bit of force on everything else, and we call this force
gravity. So when you drop a ball, the earth is exerting a force on the
ball in the same way that an engine exerts a force on a car.

One difference is that when the car is going fast enough, we stop
pushing on the gas pedal, so it doesn't _keep_ accelerating. But the
earth never stops pulling. Even when the ball gets to the ground, the
earth doesn't stop pulling. When you step on a scale, and it tells
you that you weigh ___ pounds, what it's telling you is how hard the
earth is pulling on you. If the floor were suddenly to move out of the
way (for example, if you were in an elevator that was standing still,
and the cable broke), you'd start accelerating. The reason you _don't_
accelerate is that while the earth is pulling on you, the floor is
pushing on you, and the forces exactly cancel out. It's sort of like
if four people got out of a car, and two started pushing from the
rear, and the other two started pushing from the front. They'd
generate a lot of force, but the car wouldn't go anywhere. And so we
have to amend our previous statement - whenever we apply a _net_ force
to something (that is, a force that isn't being canceled out by some
other force), it accelerates.

So what is happening when you drop a ball? There is nothing to push
upward, so the downward force of gravity starts accelerating the ball
towards the earth. And it keeps accelerating until it hits the ground.
Then a lot of other things happen that we're not going to talk about
right now. :^D

And what is happening when you throw a ball to the side? Again,
nothing is pushing upward, so gravity starts accelerating the ball
toward the earth. The ball increases its speed in the downward
direction. What about toward the side? There are no forces acting in
that direction, so it just keeps its original speed.

So if you throw two balls, one twice as fast as the other, they'll hit
the ground at the same time, but one of them will travel twice as far
to the side. Dropping a ball, then, is just 'throwing' it with a
sideward speed of zero.

There is one other important thing to know about gravity. If we put
the same engine in two different cars, one much lighter than the
other, the lighter one will accelerate more quickly. In each case,
the engine generates the same force, but in the lighter car there is
less to push.

But the force of gravity depends on how much stuff there is to pull
on. So let's say you have two balls, one of which weighs twice as much
as the other. If you drop them at the same time, from the same height,
the earth will exert twice as much force on the heavy one, but there
is twice as much weight to be moved. So the extra weight cancels the
extra force (sort of as if you bought a Porsche, but put half a ton of
iron in the trunk), with the result that the two objects end up with
the _same_ acceleration. That is, if you drop a baseball and a
cannonball at the same time, from the same height, they'll hit the
ground at the same time. In fact, if you go to a place where there
isn't any air (like the moon), you can drop a feather and a piano, and
they'll hit the ground at the same time.

if that ain't the longest wrong answer...............

It is long but it is accurate. It matches mine and it matches the Newton's cannon website above.

The wrong answers were the ones you posted.

And I still don't know how or why the moon orbits the earth and never shows its other side.

i understand that you don't know why jeannie

Tidal locking.

Thanks! That's very interesting.

i would have to say negative on that theory... so your telling me that if 2 asteroids were traveling at the same speed, and both passed the earth at about 200 miles away, and one was twice the size of the other, that the bigger one would not have any better chance at escaping earths gravity than the smaller one? i have to say BS on that.

What is the highest level physics course you have taken?

Here's some help.

The Value of g

In Unit 2 of The Physics Classroom, an equation was given for determining the force of gravity (Fgrav) with which an object of mass m was attracted to the earth
Fgrav = m*g

Now in this unit, a second equation has been introduced for calculating the force of gravity with which an object is attracted to the earth.

where d represents the distance from the center of the object to the center of the earth.

In the first equation above, g is referred to as the acceleration of gravity. Its value is 9.8 m/s2 on Earth. That is to say, the acceleration of gravity on the surface of the earth at sea level is 9.8 m/s2. When discussing the acceleration of gravity, it was mentioned that the value of g is dependent upon location. There are slight variations in the value of g about earth's surface. These variations result from the varying density of the geologic structures below each specific surface location. They also result from the fact that the earth is not truly spherical; the earth's surface is further from its center at the equator than it is at the poles. This would result in larger g values at the poles. As one proceeds further from earth's surface - say into a location of orbit about the earth - the value of g changes still.

To understand why the value of g is so location dependent, we will use the two equations above to derive an equation for the value of g. First, both expressions for the force of gravity are set equal to each other.

Now observe that the mass of the object - m - is present on both sides of the equal sign. Thus, m can be canceled from the equation. This leaves us with an equation for the acceleration of gravity.

The above equation demonstrates that the acceleration of gravity is dependent upon the mass of the earth (approx. 5.98x1024 kg) and the distance (d) that an object is from the center of the earth. If the value 6.38x106 m (a typical earth radius value) is used for the distance from Earth's center, then g will be calculated to be 9.8 m/s2. And of course, the value of g will change as an object is moved further from Earth's center. For instance, if an object were moved to a location that is two earth-radii from the center of the earth - that is, two times 6.38x106 m - then a significantly different value of g will be found. As shown below, at twice the distance from the center of the earth, the value of g becomes 2.45 m/s2.



The table below shows the value of g at various locations from Earth's center.
Location

Distance from
Earth's center (m)

Value of g
m/s2

Earth's surface


6.38 x 106 m


9.8

1000 km above surface


7.38 x 106 m


7.33

2000 km above surface


8.38 x 106 m


5.68

3000 km above surface


9.38 x 106 m


4.53

4000 km above surface


1.04 x 107 m


3.70

5000 km above surface


1.14 x 107 m


3.08

6000 km above surface


1.24 x 107 m


2.60

7000 km above surface


1.34 x 107 m


2.23

8000 km above surface


1.44 x 107 m


1.93

9000 km above surface


1.54 x 107 m


1.69

10000 km above surface


1.64 x 107 m


1.49

Since the formulas are in graphic form, they don't show up here.

To view them go to http://www.physicsclassroom.com/class/circles/u6l3e.cfm

is that a yes or a no?

I see... and it isn't a theory. They are called Newton's laws.

From the math/physics site that I posted above, "Now observe that the mass of the object - m - is present on both sides of the equal sign. Thus, m can be canceled from the equation. This leaves us with an equation for the acceleration of gravity. "

Thus the acceleration of gravity is not (ever) dependent upon the mass so the two asteroids, at the same distance from Earth, would accelerate towards the Earth at the same rate, regardless of their mass. The same concept as the two bullets, or super galactic groups near a proportionally large mass.

The table provided shows how much any mass can be expected to accelerate towards the Earth given it's distance from the surface.

The only factor, which is unrelated, that might apply is that if the asteroid was small enough and it entered the upper atmosphere, it could burn up from the friction or be caused to slow down enough from the friction to fall to the Earth where a really big one could just punch it's way through.

i know that they fall at the same speed, i'm not trying to argue that, speed and weight would be a factor when the earth is trying to pluck it from it's orbit, before gravity has caught it. a free fall is one thing, velocity x weight is another. why are smaller asteroids more likely to impact than the bigger ones?

Correct me if I'm wrong...

(I did some brief research online just to get my thoughts clear...)

My understanding is, when dealing with objects in space, velocity is more important than mass when factoring the influence of gravity.

A mass 200 miles above the Earth moving at 3,000 mph would require about 500 hours to impact Earth even at full gravity and regardless of mass. If velocity was 600 mph, then only 100 hours would be needed under the same circumstances. At 60 mph, it would take 10 hours.

In the first instance, the object would be 7x further away than the moon at the end of 500 hours. In the second, it would be about 1/4 the distance of the moon after 100 hours. Both of these would escape the Earth's pull. The third would crash into the Earth because it had only traveled 600 miles, not far enough to free itself. Remember, this is at full gravity. The further away from the Earth's surface the less the pull of gravity. The actual times would be longer, but at 200 miles above the Earth, the end results would be the same.

As far as smaller asteroids compared to larger ones...

Smaller asteroids are much more easily bumped into motion than larger ones, even in space. As a result, smaller asteroids are more likely to become strays drifting through space. A large asteroid requires something of similar size and mass - or larger - to push it into motion. Furthermore, a large asteroid in more likely to move more slowly than a smaller asteroid because of inertia. Hence a large asteroid is less likely to escape the gravity of Mars or even the moon if it came too close to either one, while the smaller asteroid may have enough velocity to pull free before succumbing to gravity.

then speed and weight are relative...the faster something is moving, the harder it is to slow it down....