What is Cars: Definition and 434 Discussions

A car (or automobile) is a wheeled motor vehicle used for transportation. Most definitions of cars say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people rather than goods.Cars came into global use during the 20th century, and developed economies depend on them. The year 1886 is regarded as the birth year of the modern car when German inventor Karl Benz patented his Benz Patent-Motorwagen. Cars became widely available in the early 20th century. One of the first cars accessible to the masses was the 1908 Model T, an American car manufactured by the Ford Motor Company. Cars were rapidly adopted in the US, where they replaced animal-drawn carriages and carts, but took much longer to be accepted in Western Europe and other parts of the world.Cars have controls for driving, parking, passenger comfort, and a variety of lights. Over the decades, additional features and controls have been added to vehicles, making them progressively more complex, but also more reliable and easier to operate. These include rear-reversing cameras, air conditioning, navigation systems, and in-car entertainment. Most cars in use in the early 2020s are propelled by an internal combustion engine, fueled by the combustion of fossil fuels. Electric cars, which were invented early in the history of the car, became commercially available in the 2000s and are predicted to cost less to buy than gasoline cars before 2025. The transition from fossil fuels to electric cars features prominently in most climate change mitigation scenarios, such as Project Drawdown's 100 actionable solutions for climate change.There are costs and benefits to car use. The costs to the individual include acquiring the vehicle, interest payments (if the car is financed), repairs and maintenance, fuel, depreciation, driving time, parking fees, taxes, and insurance. The costs to society include maintaining roads, land use, road congestion, air pollution, public health, healthcare, and disposing of the vehicle at the end of its life. Traffic collisions are the largest cause of injury-related deaths worldwide.Personal benefits include on-demand transportation, mobility, independence, and convenience. Societal benefits include economic benefits, such as job and wealth creation from the automotive industry, transportation provision, societal well-being from leisure and travel opportunities, and revenue generation from taxes. People's ability to move flexibly from place to place has far-reaching implications for the nature of societies. There are around 1 billion cars in use worldwide. Car usage is increasing rapidly, especially in China, India and other newly industrialized countries.

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  1. K

    Man needs to buy cars (combinatorics)

    Homework Statement A man needs to buy 12 cars. There are 4 kinds available. He can buy any number of cars of each kind, the condition being 12 cars in total. In how many ways can he buy the 12 cars? Homework EquationsThe Attempt at a Solution Hmmm as he can buy any number of each kind my...
  2. doglover9754

    What happens if you put a drone on hover in a moving car

    I was flying my drone last week and then it hit me. What happens to the drone if you put it in hover mode in a moving car? It must be a closed roof car and can move at any speed. But what my question is, what will happen to the drone? In hover mode, a drone will just float where it is. But if...
  3. N

    Relative velocity of two cars crashing into each other

    So I read these two other threads: https://www.physicsforums.com/threads/relative-speed-of-two-cars.642873/ https://www.physicsforums.com/threads/two-cars-colliding.740948/ And gathered what I already thought was correct, that the relative velocities of two cars of equal mass crashing into...
  4. J

    Position Functions for Two Cars Colliding on a Straight Road

    Homework Statement Two cars approach each other on a straight road. Car A is moving at 16m/s and car B at 8m/s. When they are 45m apart both drivers apply their brakes. Car A slows down at a rate of 2m/s^2 while car B slows down at 4m/s^2. Where and when do the cars collide? Homework Equations...
  5. S

    Momentum: Freight cars problem

    Homework Statement Three freight cars of equal mass are coupled together. The freight cars are traveling at 6.7m/s down a straight track when they collide with two more stationary identical cars. If all five cars are coupled together after the collision, then what is their speed if they are on...
  6. S

    Two cars driving toward each other (non-uniform speed)

    Homework Statement Two cars are 1.4 km apart and driving towards each other. One car starts from rest and accelerates uniformly at 1.2 m/s^2. The other car is driving at a constant speed of 18 m/s. When will the cars meet? Homework Equations d=vt d=ut + 1/2at^2 d=vt-1/2at^2 v^2 = u^2 + 2ad...
  7. K

    When 2 Cars With Differing Velocities Will Meet

    Homework Statement A red car moves with a constant velocity of 20m/s. Exactly 5 minutes later a blue car leaves from the same point with a constant velocity of 30m/s in the same direction as the red car. a.) For how long (time) does each car travel before meeting? b.) How far do the cars travel...
  8. A

    Do you feel safer with self-driving cars on the road?

    As a AI programmer, among other things, I know the limitations of the technology. So I vote No to this question. For one thing, safe driving demands being able to think ahead and anticipate situations which sensors do not pick up.
  9. H

    Automotive Voltage check on car electrical components

    Hi I watched this video of a guy testing a fusebox with a multimeter: if you skip to 6:10 he uses a multimeter on a particular fuse and when putting the black lead on good ground of car and red lead on either side of the fuse he gets the same reading on both sides. He even comments that there...
  10. J

    Please Check Answer -- Arrival times of 2 cars....

    Homework Statement Two cars travel in the same direction along a straight highway. One at a constant speed of 23m/s and the other at 29m/s. How much sooner does the faster car arrive at the destination 16 km away? Homework Equations Please check answer The Attempt at a Solution T23 =...
  11. T

    Assuming everything else is equal between two or more cars....

    Assuming everything else is equal between two cars, would the car with the higher horsepower have higher top speed and vice versa?
  12. Domenico94

    Electric cars -- Does periodic coasting help efficiency?

    Hi. I'm a student of electrical engineering, and I've always been interested in the idea of electrical cars, so I came up with a question: let's suppose we want to have a normal trip with car, and then we're not interested in going so fast with it. When we are driving in this condition, it isn't...
  13. C

    Car - brake locking, stopping distance

    I have been reading quite a lot about the Physics behind car dynamics and I have gotten to a point which keeps confusing me, namely - brake locking. I understand brake locking as the situation when the wheels of the car do not rotate anymore but the car is still moving - this causes the tires...
  14. mastermechanic

    Automotive Why race cars have stationary spoilers?

    I frequently hear something like "...this car have stationary spoiler like race cars" bla bla. Why are stationary spoilers used in motorsports? Active spoilers are very useful for breaking and accelerating. I want to know the reason behind it. Thanks.
  15. P

    Solving Car Collision: Velocity Impact of 40cm Rear End Impact

    Hi all, I am currently self teaching physics and have come across something i don't know how to do. There are 2 cars, Cars 1 and 2, traveling at a velocity of 60km/h (16.67m/s) in the eastern direction with a gap of 5 metres between each other. Car 2 is in front of Car 1. Car 2 decelerates to...
  16. M

    Reactions to produce electricity

    I am looking for reactions that can power a small car. I'm currently working on a college project where we have to make a car powered by a chemical reaction. Could anyone guide me in the right direction?
  17. R

    2 bumper cars collide (check my work please?)

    Homework Statement So my book doesn't have an answer for this problem at the back, was just wondering if someone could check my work.. Two bumper cars at the county fair are sliding toward one another. Initially bumper car 1 is traveling to the east at 5.62 m/s and bumper car 2 is traveling 60...
  18. S

    Automotive Why is carbon fiber safer than steel for the cars?

    Not just for carbon fiber vs steel, I went to a seminar and heard that the team was researching how to make the steel sheets used for car making to be 'stronger', so that, a car can be safer using their material. Then, when I asked what does it actually mean when they say their improved steel...
  19. Jibran96

    B What happens if two wheels turn toward each other....

    Does anyone know what will happen if the two front wheels of a car turn away from each other (left goes left and right goes right) while the car is moving or if they turn inwards towards each other? Other than the stress on the steering rod, will this cause braking and if yes, how effective can...
  20. Isobel

    Two cars moving towards each other - bullets fired

    Homework Statement This problem-solving question is about a police car chasing criminals. Two cars are moving in the same direction, parallel (assumed). One car is moving at 82 km/h. The other car is moving at 64 km/h. Bullets are fired from the car moving at 82 km/h towards the car moving at...
  21. M

    B Hey guys, I'm going to say right up front that I haven't a c

    Hey guys, I'm going to say right up front that I haven't a clue how to do these calculations, but I have a scenario that I would like the math to if anyone can help me figure it out. What I had been able to attempt to figure out doesn't seem tangible? The formulas I had researched/used was...
  22. dsfrankl

    Kinematic Equations Problem: Toy cars on adjacent tracks

    Homework Statement At t = 0, one toy car is set rolling on a straight track with initial position 16.0 cm, initial velocity -3.7 cm/s, and constant acceleration 2.90 cm/s2. At the same moment, another toy car is set rolling on an adjacent track with initial position 10.0 cm, an initial velocity...
  23. M

    Why heavy cars take more time than lighter cars to stop?

    Why heavy cars took more time to stop than lighter cars to stop when braking ?? Is it related by Inertia , if yes then why it's related by Inertia because i don't understand the physical concept of inertia
  24. farolero

    Problem with 2 cars on almost masless spining platform

    So to cars are in a circular spining platform around its center which weight is so low it can be neglected, the cars initially aim radially in opposite directions. The cars start moving radially in opposite diractions, notice net angular momentum is zero because the cars are moving radially and...
  25. PITPin

    Kinematics : two cars meeting

    Homework Statement Two cars leave at the same time (one from city A and the other from city B) and drive toward each other. They first meet d=45 km far from B . Both cars reach their destination (B for the former, A for the latter) and then start driving to their initial cities.The cars have...
  26. U

    Car chase: will the cars meet?

    Homework Statement There is a speedy car chase! A thief is getting away from a police officer. The distance between them at the start is 100m. The thief starts to accelerate at 5.0m/s^2 [F] from rest. Meanwhile the police is chasing him at its max velocity of 30m/s (sad... I know XD). Show that...
  27. S

    Automotive Vapour absorption cooling system for cars

    Is to possible to provide cooling for automobiles using vapor absorption compression system utilizing the exhaust gases? If possible how efficient can this method work?
  28. P

    Automotive Gas Turbines in Cars: Efficiency, Power & More

    I know that this topic has already been covered (kind of) in a separate forum post, but it became rather confused and there were many differing and contradicting opinions/supposed facts, so I just want to clarify a few things. Firstly, are gas turbines more or less efficient (useful mechanical...
  29. I

    Why are accelerating cars less fuel efficient?

    What is it about acceleration that makes it less fuel efficient?
  30. A

    Kinematics passing cars problem

    Homework Statement A car in the northbound lane is sitting at a red light. At the moment the light turns green, the car accelerates from rest at 2m/s2. At this moment there is also a car in the southbound lane that is 200m away and traveling at a constant 25m/s. The northbound car maintains its...
  31. G

    Automotive Powering the surrounding neighborhood using friction from passing cars

    Hi guys, I am curious to find if there is any invention where the friction between the surface of motorway and cars' tyres are used to create kinetic energy which can be converted into electrical energy to power up the houses and plants around them. Thank you.
  32. VitorPAguiar

    What are the aspects that can help a car to flip in a turn?

    I am not sure if this is the right place to ask it, but this is a question that I thought today, and it gave me some curiosity to understand. Imagine that a car will curve, we can say the turn is a bit tight , what are the factors that can help it to flip? I was wondering about some aspects...
  33. Svein

    Insights An Analysis of Road Capacity - Comments

    Svein submitted a new PF Insights post An Analysis of Road Capacity Continue reading the Original PF Insights Post.
  34. Erenjaeger

    Momentum, collision of two cars problem

    Homework Statement A 3.0 kg cart moving to the right with a speed of 1.0 m/s has a head-on collision with a 5.0 kg cart that is initially moving to the left with a speed of 2.0 m/s. After the collision, the 3.0 kg cart is moving to the left with a speed of 1.0 m/s. What is the final velocity of...
  35. Algr

    Gas Trailer for Electric Cars?

    So I was reading about Tesla's plan for battery swapping. I didn't think that was such a great idea, since you would be leaving behind something that was a good fraction of the cost of the car. Might there be a better way?: So, it's the future: You've been driving around town, and used up...
  36. Alisdair

    Automotive Electric cars without clean energy supply....

    Hello all. I'm pretty disorganised and not very clever so I thought I'd ask you all... If you charge an electric car from a power station run on fossil fuel is it cleaner than a petrol car? I'm wondering after looking at the energy loss in converting fossil fuel to electricity and then in...
  37. N

    1D Kinematics: Distance between 2 cars

    Homework Statement Car A is traveling a distance d behind Car B. Initically both cars are traveling at the same speed of 60 ft/s. Suddenly Car B applies the brakes, causing Car B to decelerate at 8ft/s2. It takes the driver of Car A 0.75 seconds to react, and when she applies her brakes Car A...
  38. B

    Ratio of Power between Two Cars

    Homework Statement A Grand Prix race car accelerates to twice the speed of the car in sample problem 1, in the same amount of time. Calculate the ratio of the power needed by the Grand Prix car to the power needed by the car in sample problem 1. Given: initial speed of car=0m/s, final speed...
  39. Praline

    Help with rolling cars -- science project

    I'm sure this is elementary for this forum, but can someone help me figure out if my son's science fair project results are correct? He rolled his toy car, with and without weight added, down hill and measured the time to get to the bottom of the hill and the distance traveled once the car hit...
  40. G

    Cars: Wheel Angle & Turning Circle Radius

    My question is, if a car is moving at speed V, and its front wheels are at an angle (theta), what is the relationship between the angle of the wheels relative to them being parallel with the car and the radius of the circle at which the car goes around. Thanks.
  41. M

    Would this work to decrease air resistance in sports cars?

    Okay so here is my idea, not really sure how well (if at all) it would work but I am wondering if it would be possible (assuming battery technology is good enough) to ionise air in front of a formula 1 car (or plane or whatever) giving it a charge (like the way lightning works) , then creating...
  42. A

    How many Newtons would it take to damage a car?

    I am working on a science project, just in my spare time, and for this project I needed to know the amount of force it would take one car to damage another car, but the same model (so same weight, strength etc.) thanks for you help ~ Alex
  43. Greg Bernhardt

    What 20k race cars on a track looks like

    This is a simulation and some of the crashes are really epic!
  44. J

    Cars attaching to one another using magnetic force

    hi, i'm doing a little research and in need of help since I'm not so talented in physics.. :( Is it possible to attach 2 cars with magnetic force so that they can be driving as one? (one car in the front and another car behind) I think it can be done with magnetic force but how.. Also, Is it...
  45. C

    The correct usage of self driving cars in SF

    Setting: generic, mildly futuristic, nothing that would put you in awe. I rather want to discuss in general terms how get in near future SF correctly usage of self driving cars right with technologies that should realistically accompany them. And get right any social consequences. Thanks to...
  46. C

    Automotive Could cars have a better fuel economy at low speeds?

    The part that I roughly understand: 1) Drag equation, drag increases by square of velocity, thus if it was only factor to be taken into account then the lower speed the better. 2) In case of cargo ships there is a policy of decreasing speed to reduce fuel usage, called "slow steaming". It...
  47. L

    Automotive How can gears improve the performance of mousetrap cars?

    Hey, so I have a project for an intro engineering course in which we have to build a mousetrap car that both moves quickly and goes long distances. I've scoured the internet for info and I've come up with a few questions. First off, as I understand the physics of the mousetrap car, the...
  48. D

    Two cars with constant acceleration meeting

    Homework Statement Two cars travel towards one another on a 21.0m road, the car traveling to the left has an acceleration a_L=2.4m/s^2 the other car an a_R=1.8m/s^2. What is the distance traveled by the left car up to the meeting point? Homework Equations Left Car...
  49. S

    Wave speed of the collision process in a line of cars

    Homework Statement I need to write an equation for the at rest at a stoplight. Each car bumps into the one in front of it until the first car in line gets bumped. Homework Equations I found these equations for wave speed: V=√(T/(m/L)), where T is tension, m is mass, L is length and of...
  50. E

    Velocity after 2 cars collide

    Homework Statement A 2000-lb car traveling north at 60 mph collides with a 5000-lb car traveling east at 40 mph. The cars stick together after the collision. Find the velocity (magnitude and direction) of the cars just after the collision. Homework Equations conservation of linear momentum...
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