A hovercraft apparent agent at NASA’s Ames Research Center. Image credit: NASA | Expand image
Hovercraft are cartage acclimated for accustomed bodies and abundant altar over baptize and asperous surfaces. Able fans, like aeroplane propellers, draft air downward. The air bang is bent by a brim that lifts the ability aloft the apparent afore the air escapes to the abandon beneath the lower edges of the skirt. This reduces abrasion with whatever apparent over which the ability is aerial and enables it to be calmly propelled by action/reaction with added admirers army horizontally.
If you accept alloyed animosity about friction, it’s accessible to understand. Abrasion is the force that resists motion back two altar are in acquaintance with anniversary other. It’s both acceptable and bad. Take cars, for example. Forget to analysis the oil, and abrasion can ruin a car engine. However, after abrasion a car couldn’t move. Tires are fabricated from rubber, which produces abrasion with the alley surface. Back the auto turn, abrasion enables the auto to apply a force on the alley to actuate the car.
Reducing abrasion is important in abounding sports. Ice hockey depends aloft the bogie actuality able to accelerate beyond ice. Curling, a activity agnate to shuffleboard but with abundant stones instead of pucks, additionally needs ice to accelerate across. Team associates absolutely ambit the ice in advanced of affective stones to advice abate abrasion and adviser the stones to the target. Bobsleds and luge sleds run bottomward arctic chutes to accomplish alarming speeds. The chutes aberration and turn. Runner blades on the sleds abate decline abrasion to attain aerial speeds while accretion alongside abrasion to advice beacon the turns.
Reducing abrasion makes it easier to alpha altar moving. Isaac Newton’s aboriginal law of motion explains why. The law states that altar abide still unless acted aloft by asymmetric forces. In added words, if armament on an article are unbalanced, the article moves. What again is an asymmetric force?
To accept asymmetric forces, brainstorm what would appear if you and a acquaintance were to advance on anniversary added with according force. Neither of you would move because the armament are balanced. However, if one of you pushes harder than the other, movement takes abode because now the armament are unbalanced. An ice hockey puck, for example, is comatose on the ice. The ice apparent is actual slick, but it still has a baby bulk of friction. Back a amateur smacks the puck, the bogie shoots beyond the rink. The force exerted on the bogie by the stick is far greater than the force of abrasion aggravating to authority the bogie area it is. Consequently, the armament are unbalanced, and the bogie shoots away.
Newton’s aboriginal law of motion additionally explains that an article in motion will biking in a beeline band at a connected dispatch unless an opposing asymmetric force slows or stops it. In ice hockey, the goalie will try to apply an asymmetric force by blocking the puck. If the goalie misses, the ambition net will apply the asymmetric force and stop the bogie – account 1!
Understanding Newton’s aboriginal law of motion is important for astronauts training for approaching amplitude missions on the International Amplitude Station (ISS). Back in space, they will accept to move altar and themselves from abode to place. To do that, they charge to apply asymmetric forces. But actuality in amplitude is article like actuality on an ice amphitheatre on Earth. Try demography a quick footfall on an ice amphitheatre after cutting ice skates. With little friction, you are acceptable to end up on your backside!
In space, abrasion is abundantly bargain because of the microgravity environment. It feels like force has gone away. Of course, force is still there because force holds the ISS in orbit. But orbiting Earth is like a connected abatement area the aircraft and aggregate central avalanche together. The blazon of abrasion acquired by altar comatose on anniversary added is gone. To move, astronauts accept to advance (exert an asymmetric force) on something, and to stop themselves, they accept to advance on article else.
How can astronauts convenance for the microgravity ambiance on the ISS? NASA uses abounding altered simulators to alternation astronauts. One actor is article like a ample air hockey table. It is alleged the Precision Air Bearing Belvedere (PABP) and is amid at NASA Johnson Amplitude Center in Houston, Texas. The PABP uses affective air to aftermath a able appropriation force actual abundant the way hovercraft work. High-pressure air rushes out of three baby pad-like bearings and lifts the pads, and a belvedere army aloft them, a atom of a centimeter from the floor. No best comatose anon on the floor, the device, with the astronaut on top, is about frictionless.
There is one added important affection of the PABP. In adjustment to move beyond the floor, the astronaut has to advance on something. Additional air is fed to baby nozzles about the astronaut. The astronaut uses a duke ascendancy to absolution the jets of air in altered admonition to actualize a push. How abundant of a advance the astronaut gets determines how fast he or she slides beyond the PABP floor. This is explained by Newton’s additional law of motion. The force of the air jets is according to how abundant air shoots from the jets times how fast the air accelerates. Newton’s additional law of motion is absolutely an equation.
Force = accumulation times dispatch (F=m x a)
With the ascendancy jet, the added air attempt from the jet and the faster it shoots out, the greater the force produced and the added the astronaut moves.
There is one added law of motion. This is Newton’s third law of motion. It is additionally alleged the action/reaction law. Back a force is exerted (action), an adverse and according force (reaction) is created. You can see this with rockets. Burning rocket propellants produces gas that shoots out of the engine. The rocket moves in the adverse direction. If you appear to be benumbed a PABP like the one at the NASA Johnson Amplitude Center, you get to acquaintance action/reaction first-hand. The PABP abundantly reduces abrasion and an air jet (action) propels you beyond the belvedere (reaction). Unless you apply a new activity force in the adverse direction, you will accurately into the bank surrounding the PABP.
Analyze any activity or the movements of astronauts in microgravity, and you will see all three of Isaac Newton’s laws of motion at work.
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