<s id="A18-2.34.03">Why do wagons with two wheels carry</s>
<s id="A18-2.34.04">the loads more easily than wagons with four wheels?</s>
<s id="A18-2.34.05">Because the load on wagons with two wheels is distributed in two equal parts to both sides of the axle.</s>
<s id="A18-2.34.06">That won't do for wagons with four wheels; the load cannot be distributed in a way that the two parts of it are equal on both sides, but the entire load lies in front of the rear wheels and behind the front wheels, and the difference in the position determines the speed of the motion of the wheels; for the wheel only has a fast motion, since its load rests equally on all of its parts.</s>
<s id="A18-2.34.07">b. </s>
<s id="A18-2.34.08">Why is the pulling of a wagon in sand hard for draught animals?</s>
<s id="A18-2.34.09">Because part of the curvature of the wheels is in the groove of the sand and, when the wagon is pulled, the sand, that is in front of the wheel, supports it.</s>
<s id="A18-2.34.10">Furthermore it is difficult because the feet of the animals go into the sand and it is hard to pull them out.</s>
<s id="A18-2.34.11">This, however, does not happen on hard ground. </s>
<s id="A18-2.34.12">c.</s>
<s id="A18-2.34.13">Why does the same weight cause different inclination in balances that are in equilibrium, in a way that there is a greater inclination with a lesser load?</s>
<s id="A18-2.34.14">If one has, for example, two scales with three mines in each, and we put another half mine into one of the two scales, then this scale inclines very strongly.</s>
<s id="A18-2.34.15">If there are, however, ten mines in each of the scales, and we add half a mine to one of the scales, then the inclination of the beam is very small.</s>
<s id="A18-2.34.16">Because the first case shows that the load is moved by a great force, the three mines being moved by the same plus a sixth of it; the ten mines, however, are moved by the same plus a twentieth of it.</s>
<s id="A18-2.34.17">For one half mine is the twentieth of ten, but a sixth of three mines, and the load that is moved by the greater force is easier to be moved.</s>
<s id="A18-2.34.18">d. </s>
<s id="A18-2.34.19">Why do big loads fall to the ground in a shorter time than lighter ones?</s>
<s id="A18-2.34.20">Because, as it holds for them that they can be more easiy moved if the force moving them from outside is greater, they also move more quickly, if the force within them is greater.</s>
<s id="A18-2.34.21">The force and the attraction are, however, greater for the bigger load in natural motions than for the smaller load.</s>
<s id="A18-2.34.22">e. </s>
<s id="A18-2.34.23">Why does the same weight, if it is wide, fall more slowly to the ground than if it is spherical?</s>
<s id="A18-2.34.24">Not because, as some believe, the wide one in its breadth meets with a lot of air, the spherical however, because its parts meld into each other, only meets with little air, but because the load that sinks wide has many parts, to each of which, according to its breadth, comes a part of the force, so that in the motion of this load each of its parts receives some of the moving force according to its weight, but one force does not meet it as a whole.</s>
<s id="A18-2.34.25">f. </s>
<s id="A18-2.34.26">Why does a shot from the center of the string propel the arrow into a great distance?</s>
<s id="A18-2.34.27">Because the tautness there is the strongest and the propelling force the greatest.</s>
<s id="A18-2.34.28">That is why one makes the bows from horns, because here bending is possible.</s>
<s id="A18-2.34.29">When they are strongly bent, the string with the arrow is more strongly drawn, so that a greater force gets into it and it therefore covers a longer distance.</s>
<s id="A18-2.34.30">That is why hard bows whose ends cannot be bent only propel the arrow a short distance.</s>
<s id="A18-2.34.31">g. </s>
<s id="A18-2.34.32">Why can wood be broken more quickly if one's knee is brought into its center?</s>
<s id="A18-2.34.33">Because, if one's knee is brought into a smaller distance (form one end) than the center, so that one of the two parts is shorter than the other one, then it is a balance divided into two unequal parts, which is why the hand that is further from the knee has the superior weight over the one closer to it.</s>
<s id="A18-2.34.34">The one reaches, however, the force of the other one only when both are at the end of the [piece of] wood (at an equal distance from the center).</s>
<s id="A18-2.34.35">h. </s>
<s id="A18-2.34.36">Why is a piece of wood, the longer it is, the weaker and why does its bending increase when it is raised at one of its two ends?</s>
<s id="A18-2.34.37">Because in the long [piece of] wood great force is distributed over its parts so that the whole has the superior weight over its solid part, on which it rises.</s>
<s id="A18-2.34.38">Therefore, here the same phenomenon occurs as in a short [piece of] wood, when from its ends something is suspended that presses it down.</s>
<s id="A18-2.34.39">Thus the increase in length of the [piece of] wood corresponds to the weight that pulls down the shorter [piece of] wood. </s>
<s id="A18-2.34.40">Therefore the same [thing] happens to the long [piece of] wood, because of its length, as [happens] to the short [piece of] wood, when something heavy is tied to its end.</s>
<s id="A18-2.34.41">i. </s>
<s id="A18-2.34.42">Why does one use pliers when pulling teeth, and not the hand?</s>
<s id="A18-2.34.43">Because we cannot grip the tooth with the entire hand, but only with part of it; and just as it is harder for us to lift a weight with only two fingers, than with the entire hand, so it is also harder for us to grip the tooth with two fingers and to press, than with the entire hand.</s>
<s id="A18-2.34.44">In both cases the force is the same but the division of the pliers in its nail causes the hand to have the greater strength than the tooth; for it is a lever, at the greater part of which is the hand, and the space of the pliers makes the moving of the tooth easier.</s>
<s id="A18-2.34.45">For the root of the tooth is that around which the lever moves.</s>
<s id="A18-2.34.46">But since the space of the pliers is greater than the root of the tooth, around which something big moves, the hand outweighs the force resting in the root of the tooth.</s>
<s id="A18-2.34.47">For there is no difference between the moving of a weight and the moving of a force which equals that weight.</s>
<s id="A18-2.34.48">For if we close the hand after it was stretched out, then a resistance occurs, not because of the weight of the hand, but because of the force with which the muscles adhere to one another.</s>
<s id="A18-2.34.49">k. </s>
<s id="A18-2.34.50">Why can balances, be they loaded or not, be moved faster if one turns them (horizontally) than they move to one side, towards which one inclines them?</s>
<s id="A18-2.34.51">Because, when one turns them, their weight remains positioned similarly and evenly in all directions, so that it thus rotates around a center, namely the point of suspension.</s>
<s id="A18-2.34.52">But if we pull the balance to one of the two sides, then we lift a load, because the drop of the one scale pushes the other one up, so that its motion is not natural, I mean the motion upward of a load; for the natural motion is easy, namely the attraction downward of a weight.</s>
<s id="A18-2.34.53">Therefore it is easier to pull weights downward than to lift them upward.</s>
<s id="A18-2.34.54">l. </s>
<s id="A18-2.34.55">Why is it easy to move suspended weights?</s>
<s id="A18-2.34.56">Because the entire force of the weight is outweighed by the force through which it was suspended.</s>
<s id="A18-2.34.57">Thus, because they do not have great force left, it is easy to push them.</s>
<s id="A18-2.34.58">The same we also see in scales; when it is suspended and we pull it, it moves very easily.</s>
<s id="A18-2.34.59">m. </s>
<s id="A18-2.34.60">Why are the stone [block]s of considerable size that are found at the shore of the sea mostly round?</s>
<s id="A18-2.34.61">Because they were first sharp-edged, but through the motion of the sea one bumps into the other, so that the edges break against one another because of their weakness.</s>
<s id="A18-2.34.62">n. </s>
<s id="A18-2.34.63">Why is it harder to move suspended loads that one wants to move, the further one removes the hand from them, until it reaches the firm support that they are suspended from, or comes close to it?</s>
<s id="A18-2.34.64">Because, if we want to move them in the firm place that they are suspended from, this is very hard for us, and completely impossible.</s>
<s id="A18-2.34.65">But if the hand moves away from the firm support, then the weight moves, though with difficulty, namely because it is still too close to the point where motion stops completely.</s>
<s id="A18-2.34.66">Yet the further the mover goes away from the firm support, the easier the moving becomes to him.</s>
<s id="A18-2.34.67">Let us, for instance, imagine the firm support that the load is suspended from at point <a> and let the rope be the line <ab>.</s>
<s id="A18-2.34.68">Let us now draw the line <ag> perpendicular to <ab> and let us assume on line <ab> two randomly positioned points, <d> and <e>, and pull the rope at point <d>, then we brake it, until it takes the form of <azh>.</s>
<s id="A18-2.34.69">Then the load is at <h>.</s>
<s id="A18-2.34.70">Now I say that <h> lies higher than <b>. Proof.</s>
<s id="A18-2.34.71">If we extend line <hz> towards <g>, then, since <azh> is greater than <gzh>, point <h> is higher than point <b>.</s>
<s id="A18-2.34.72">Let further the rope to be tightened at point <e> have a position perpendicular to <ag> so that the load is again in the same place, namely the same as <ab>.</s>
<s id="A18-2.34.73">Since now <ae> is greater than <az>, <e> will come to rest lower than <z>, at approximately <q>.</s>
<s id="A18-2.34.74">If we now pull <aq> then <ab> is broken towards <aqh>.</s>
<s id="A18-2.34.75">Now I say that the suspended weight comes lower than <h>.</s>
<s id="A18-2.34.76">Proof.</s>
<s id="A18-2.34.77">Since <az> plus <zq> is greater than <aq>, then, if <hq> is added to both sides, <az> plus <zh>, i.e., <ab>, is greater than (<aq> + <qh>).</s>
<s id="A18-2.34.78">Let now (<aq> + <qk>) equal <ab>, then the load comes to <k>, and <k> lies lower than <h>.</s>
<s id="A18-2.34.79">Thus if we pull the load from <e>, it comes to <k>; if we pull it, however, from point <d>, then it reaches <h>, so that the load is lifted higher from point <d> than from point <e>.</s>
<s id="A18-2.34.80">The load, however, that is lifted to a higher point, strains the force more than the one lifted to a lower point, because the one lifted to a higher point takes more time.</s>
<s id="A18-2.34.81">o. </s>
<s id="A18-2.34.82">Why do objects that are floating on water have a greater speed if they are lying on only one side?</s>
<s id="A18-2.34.83">Because the part above water is very light, so that the water supporting it is also very little and the wind that hits it, has greater strength than the water that resists its motion.</s>
<s id="A18-2.34.84">p. </s>
<s id="A18-2.34.85">Why does the rudder, although it is very small, deflect big ships?</s>
<s id="A18-2.34.86">Because a man who runs and whom someone pulls to any side, quickly turns towards that side.</s>
<s id="A18-2.34.87">The rudder however is supported by the water, so that it has greater strength than the ship.</s>
<s id="A18-2.34.88">q. </s>
<s id="A18-2.34.89">Why do arrows penetrate into coats of mail and armor but not into spread-out canvas?</s>
<s id="A18-2.34.90">Because the weapon, when it hits an object that gives way to it and does not offer resistance to it, does not have a great effect, since the speed and the size of the force splits when hitting a yielding and non-resistant object.</s>
<s id="A18-2.34.91">If, however, something hard hits something equally hard and gives it a blow, then the hard object does not give way and offers resistance, so that nothing of the force splits, but the impact is a strong one.</s>
<s id="A18-2.34.92">For the same reason there is no damage to those who fling themselves into the water from a great distance.</s>
<s id="A18-2.34.93">r. </s>
<s id="A18-2.34.94">Why do liquids that are heavy in nature move quickly with ease?</s>
<s id="A18-2.34.95">For we see that a single man moves one thousand Kist of water at the same time.</s>
<s id="A18-2.34.96">Because water is a homogenous object, whose parts can, however, quickly be separated.</s>
<s id="A18-2.34.97">Therefore it does not have any firmness in itself but it flows downward.</s>
<s id="A18-2.34.98">That's the reason why we move only a small part of it and the remaining parts incline towards the place where the small part of it has been brought.</s>
