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  • Category: Technology

    How many forces áct on a car to resist while in motion ?

    Have a query about forces associated with a car in motion? Find advice from experts on this page.

    I want to know: How many forces acts on a car to resist its motion and when it comes to rest?
    And how much weight it can carry?
    What is the formula which determines the weight carrying capacity of car?
    I also need a attachment of that formulas.
    Awaiting response.
  • #139704
    When any object is in motion it goes through three forces acting on it. First is centripetal force which applies while the object in motion. And centrifugal force that acts against the motion of object. And finally the gravity that affects the objects. There are few other forces that affects such inertia and friction as well.

    Amount of weight car can carry depends on F = ma. Here mass = mass of car, a is acceleration and F stands for force. Alternatively you can use F = m* v^2 / R. This can help you find the weight of the car. If you know the other values from the equation.

  • #139708
    As the car is in motion, the dragging force comes into play which would retard it's motion. Here the chief resistance in retardation of motion is the air. This is in consonance with Newtons Third law of motion stating that every action is opposite and equal .
    When the car is at rest, the inertia would act on the body of the car and it would offer substantial resistance to keep the car moving.
    While it is in motion, some frictional forces are also operative and are expressed as F= mew multiplied by R. Where mew denotes to Coefficient of friction and R is the resistance.
    On stationary position of the car, the reaction - force, R will be equal to mg- where m stands for mass of the car and g is the acceleration due to gravity.
    The weight of the car can be calculated by the formula P = mf where P is the force and m is the mass and f is the acceleration. Knowing P and f, m can be calculated. If m is expressed in kg and g is in Newton then the unit of force will be in kg - wt.

  • #139715
    There acts 4 forces on a car while moving in straight line and two while in rest
    while moving
    1. wt of car=mg
    2.Reaction to wt=N(normal)
    3.F=ma=force moving the car forward, (a is acceleration and m is mass)
    4.Drag or retardation or reaction to F
    while in rest
    1. wt of car=mg
    2.Reaction to wt=N(normal)
    see the sketch for the position and direction
    what load a car can carry it depends on F=MG=mg+load
    if we ignore structural factor see only force it is the power of engine which is directly related to load carrying capacity.

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  • #139748
    First you need to prepare a free body diagram which represents all the forces which are acting on car while in motion. Then you need to determine the dominant force which resists the motion of the car.

    (1) The weight of the car is acting downwards,
    (2) The force of friction will act in opposite to the car direction
    (3) Skin friction or drag of air which ultimately acts on the car engine to retard its motion
    (4) The reaction forces are normal to the car due to its weight
    (5) The pull force given by engine

    Now, in order to retard the motion of car, you need to first find the resultant force on car. Then you need to change the forces so as to retard the motion of the vehicle.

    By this calculation, even you can find the total weight that your car should carry keeping your engine of car to be able to pull it.

    Dr. Paresh B. Gujarati.
    Mechanical Engineer.
    'I'mprovement always begins with 'I'.

  • #140387
    The forces acting on a moving car are thrust and drag which are the same forces that act on a stationary car.
    Drag is the force of air resistance (a form of friction) pushing against the front of the car while it is moving. Thrust is the force pushing the care forwards. Thrust comes from the engine turning the wheels.
    If the forces of thrust and drag are equal, then forces are balanced and the car will move with constant velocity. If forces of thrust and drag are not equal, then forces are unbalanced and car will accelerate. Car will get faster if thrust is bigger than drag and slower if the drag is bigger than the thrust.

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