Mechanics

Yes, cars have less friction when they roll on the ground than when the breaks are on (sliding). That's why breaks stop the car, because the sliding friction of rubber on asphalt is very high.

In a simple case of lifting a weight using a pulley, there are two ways to do it and two different results.

First, attach a pulley to the ceiling, and a rope to the weight which is on the floor. Run the rope through the pulley. Now we simply pull down on the rope and the weight is lifted up.

In the second case, we attach one end of the rope to the ceiling, the pulley to the weight, and pass the unattached end of the rope through the pulley. Now we have to pull the rope up, and the weight is lifted.

Now let's look at each job and what happens.

In the first case, pull the rope tight without lifting and hold the rope at the top, next to the pulley. If you now pull the rope all the way down to the floor, the weight goes all the way up to the ceiling. Note also that the tension in the rope is equal to the weight being lifted and that there is only one tensioned rope pulling the weight upwards. Passing over the pulley changes the direction of the tension in the rope but doesn't change it's pulling power. Pulling that rope from ceiling to floor is exactly the same as lifting the weight from floor to ceiling.

In the second case, tighten the rope before lifting and hold the rope where it exits the pulley on the weight. Now pull and your hand moves from there to the ceiling - about the same distance (but the other way) as you moved your hand in the other case. However, notice now that the weight is only half way to the ceiling. It is hanging on a loop of rope, one side going to the hook and the other going to your hand. This suggests that the weight is shared by these two parts of the rope and therefore the tension in each piece only needs to be half the weight. Your hand is holding half the weight. The ceiling hook is still holding the other half.

To finish the job, you will have to keep pulling more rope - all the rope which is still there from hook to weight pulley and back to your hand. That's the floor to ceiling distance. In the second case, you pull twice as much rope to finish the job.

And because it takes twice as long, it only needs half the force at any stage.

Mechanical waves are waves that require a medium in which to travel, i.e., a solid or fluid. As sound needs a medium to travel, sound is a mechanical wave.

The spring constant is a measure of stiffness - the ability to resist displacement under a load. It is denoted by K where

F = kx where f = load force and x = displacement

Mass times gravity is weight. The units for weight are: -newton (N) which is equivalent to kg*m/s^2 -kilogram-force (kgf or kp as kilopond) which is eqivalent to force by which an object with mass of 1 kg is pulled in area, where gravitational acceleration is 9.80665 m/s2 1 kgf equals 9.80665 newtons.

Forces that are equal in size but opposite in direction are called balanced forces.

Yes. A non-zero force may not be sufficient to alter the velocity - for example if it is smaller that the limiting friction. No change in velocity implies no change in momentum and so impulse = 0.

When an object is falling in a gravity field, its mass does not affect its acceleration. If under the influence of friction then it takes more energy to accelerate it the larger mass it has, here on Earth. The larger the mass the more potential it has to do work if it is above the surface of the earth than a smaller mass. But in turn, to get it to the higher point more work must be done for a larger mass than a smaller mass.

According to classical mechanics, the mass of an object is constant, and cannot change. However, modern physics shows that the mass of an object can be converted into energy, and energy into mass, at high speeds. This phenomena has been proven by experiments.

Waves need not require medium to travel through. Only Mechanical waves like sound waves require medium to travel through.

Electromagnetic waves travel in vaccum like light waves.

Some waves transmitted in a medium due to disturbances in the medium .

speed = distance/time

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you calculate speed by the equation m/sec or cm/sec. This means that you would divide the distance by the time it took.

Actually to measure the speed of light is an interesting and intelligent task done by the scientists. Because the speed of light is 300,000 km in one second which is actually incredible. Out of all those, Michelson's rotating octagonal mirror method is very important. In his experiment the equation to calculate the speed of light is

speed of light = N n D. Here N = 8 as octagonal rotor is used. n - the number of rotations made by the rotor in one second. D - the total distance travelled by light.

Michelson did this experiment keeping the observatory on one mountain, Mt.Wilson and a reflector on another mountain, Mt. Antonio separated by some 35 km.

A drilling machine is able to hold a certain diameter of drill(in what is known as a chuck), and rotates at a specified rpm(revolutions per minute) enabling the drill to start a hole. the rpm of a drill is calculated by: cutting speed divided by the diameter of the drill times 300.

If the question is regarding oil & water well drilling machinery - it's a little more complicated. Typically, oil, gas, and water wells are drilled using what is called a 'mud rotary' system. A drill rig with a derrick suspends the drill pipe (20-30ft long tubes made of steel that a threaded together) inside the bore hole. A drill bit is attached to the other end. They then rotate this assembally inside the hole & let the weight of the bit & drill pipe settle on the bottom & cut the material from the bottom of the hole. A drilling fluid is pumped down the drill pipe and out the end of the bit, from there the fluid circulates back up to the surface, and is either disposed of (when using air as a fluid) or recycled & cleaned to go back down the bore hole. The fluid acts as a cooling agent for the bit, and also suspends & lifts all the cuttings out of the hole, allowing the bit to cut more material from the bottom.

Typically, smaller mobile drill rigs weigh in excess of 50,000 lbs, have 35ft derricks, and use 20ft drill pipe segments to drill with. They can be delivered with on board compressors that deliver up to 1070 cubic feet per minute of air at 350 psi, and/or mud pumps that pump hundreds of gallons of mud slurry per minute at very high pressures (500 psi +-). The derricks are usually able to hold 30,000lbs or more of drill rod & bits in the hole. A 4.5" diameter drill pipe, 20' long, with a 3.5" ID, weighs approximately 360lbs - so a 3000' hole can have up to 150 drill pipes, plus bit & stabilizers, weighing in excess of 54,000lbs.

No it does not, as a raindrop falls to earth it will gradually slow due to the changing terminal velocity. As a raindrop falls, water will evaporate from it causing the mass to decrease faster than the size and surface area. this will leave the raindrop with a higher surface area to mass ratio. Since air resistance is related to surface area and mass, the smaller raindrop will have more air resistance for its mass and will fall slower.

a washing machine, electrons orbiting in an atom, and the most important is satellites revolving around earth.

If you've got the fuel and the patience to keep it up long enough, then your speed

doesn't matter. Just keep at it, and eventually you'll get out there.

But if the amount of fuel you can carry is limited, then you want to use every ounce

of what you can carry in a way that will do you the most good in your effort to break

free of Earth. That means you want to get a short, massive boost, and reach 7 miles

per second by the time you're out of the atmosphere. At that moment, you can be

out of fuel, because at that speed, gravity can no longer pull you back to the surface.

Friction is determined by the formula Friction = μFN or alternatively Friction = μFGcos(θ).

Therefore the two factors are: (1) the coefficient of friction that depends on the two particular materials (μ) and (2) the normal force operating on the object that is pressing against a larger surface (FN / μFGcos(θ)). Normal force itself has three components upon which it depends: (a) the mass of the object upon which the force acts, (b) the gravity of the body on which the events take place (usually Earth), and (c) the angle of the surface as it deviates from a straight horizontal surface.

Quite well. A ratchet, which is actually the whole of the mechanism, has a gear (ratchet wheel) and pawl in it. Let's look inside and see what's there and how it works. The ratchet wheel is sort of like a "regular gear wheel" except that its teeth or cogs are cut with a sloped side and a "straight" or "offcut" side. That's in contrast to the two sloped sides of the tooth or cog on a regular gear wheel. Additionally, there is usually a curve in the slope of the "regular" side that acts as a ramp for the pawl to ride on. The pawl, which is usually spring loaded to keep it engaged with the teeth, will, when the ratchet wheel is rotated in one direction, slide up or "climb" the slanted or sloped side of a tooth. The pawl will then "jump" down into the bottom of the tooth space after going over the tip of the tooth, and the spring will have pushed it there. It will then ride up the next slope on the next tooth as the ratchet wheel moves in the same "forward" direction. But if the ratchet wheel is rotated in a "backward" direction, the pawl will only allow movement until it comes in contact with the "straight" side of the next tooth back, and it will jam there. This will limit backward movement of the ratchet wheel to a tooth length and no more, as long as the pawl is acting normally to check the backward rotation. There is no requirement that either the teeth or pawl have a given "cut" or "straight side" except that the ratchet wheel and the pawl, working in concert, will serve to jam the mechanism when an attempt is made to turn the ratchet in the "backwards" direction, and will allow free movement when turned in the "forward" direction. The ratchet mechanism is used in tools of the same name (ratchet). We've probably all seen them if not actually used them. The ratchet has sockets which can be slipped on a (usually square) drive of the tool so the setup can be used to turn fasteners. The ratchet mechanism is also applied to mechanical jacks which are used to lift vehicles for tire changes by the roadside. It is also applied as a pulling or lifting machine (the so-called come along winch) or in the tightening mechanism for cargo straps that truckers and aircraft loadmasters rely on. Wikipedia has a nice post on a ratchet showing the ratchet wheel and pawl. You'll find a link to that post below. There is also a link to an animated display of the function of the mechanism.

If there is zero net force, then any force acting upon the object is countered by a force equal in magnitude, and opposite in direction.

For instance, an object on a level plane has zero net force, as it is being pushed down by gravity, at a rate of 9.8 meters per second per second [(m/s)/s], and is being pushed back up by the plane at the same rate.

If you were to add a breeze from the north that impacted and created a force that was the mass of the object times 2 (m/s)/s, and yet the object still did not move, that means that there is still zero net force, as friction is now pushing north at the exact same rate as the wind is pushing south.

it is directly proportional to frequency so if frequency increases wavelength also increases

Here's the trick. Rolling friction is static friction. Sliding, or kinetic, friction is another thing, but when an object rolls without slipping, the point touching the ground at any instant is not moving at all, and so is subject to static friction.

Interference.

Mass is the measure of an object's inertia, which is a body's tendency to resist acceleration.

Ben-jammin's answer: mass is the amount of matter an object has. it's used to calculate weight with the formula (mass)x(gravity) = weight.

Some of the things that are commonly conducted are sound, heat, and electricity. All three of these can be conducted in any of the phases of matter, although solids and liquids are generally better conductors than gases.

Sliding friction is the friction between the body and the surface on which the body is sliding. Static friction however, is the friction when the body isn't moving when you aply force to it. The force of static friction is the same as the force you are pushing the body UNTIL it moves!..It's a fact that the static friction coefficient is a bit bigger than the sliding friction coefficient.