What Is the Main Force Driving a Car's Acceleration?

In summary, the conversation discusses the forces involved in a car's acceleration and how friction plays a role in the process. While some sources state that static friction is the only external force causing the car to move forward, others mention the driving force and friction as separate forces acting on the car. It is determined that friction is the force responsible for accelerating the car, with the backward arrow in textbooks possibly representing other friction forces acting against the car's motion.
  • #1
davon806
148
1

Homework Statement


When the wheels rotate backwards,a backward force is exerted on the ground by the tyres.
By 3rd law,a equal but opposite force acts on the tyre by the ground,so the car
accelerates.
But I have also found some websites that states static friction is the only external
force causing the car to move forwards.
In some typical physics questions,the driving force and friction are two different
forces act on a car,where friction is in the opposite direction of displacement.
I would like to ask which force is actually accelerating the car?Friction or reaction
force by the ground(due to the engine)?
If it is friction,why backward arrow is drawn in some textbooks to represent friction while
the car is accelerating forwards?


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  • #2
davon806 said:

Homework Statement


When the wheels rotate backwards,a backward force is exerted on the ground by the tyres.
yes, this is a friction force
By 3rd law,a equal but opposite force acts on the tyre by the ground,so the car
accelerates.
yes, by friction
But I have also found some websites that states static friction is the only external
force causing the car to move forwards.
that is correct
In some typical physics questions,the driving force and friction are two different
forces act on a car,where friction is in the opposite direction of displacement.
the driving force (or traction force) is the friction force on the driving tyres acting forward; friction on the non driving tyres acts backwards
I would like to ask which force is actually accelerating the car?Friction or reaction
force by the ground(due to the engine)?
friction is the reaction force, accelerating the car
If it is friction,why backward arrow is drawn in some textbooks to represent friction while
the car is accelerating forwards?
maybe they are showing the forces acting on the ground by the tyres and not the force on the tyres from the ground..?
 
  • #3
davon806 said:
If it is friction,why backward arrow is drawn in some textbooks to represent friction while
the car is accelerating forwards?

That's probably showing the other friction forces like air resistance and rolling friction that are tending to slow the car down and so act backwards.

That's separate from the reactionary friction force on the wheels driving the car forward.
 

1. What is the force that accelerates a car?

The force that accelerates a car is the engine's power, which is converted into the car's motion.

2. How does the engine's power accelerate a car?

The engine's power creates a force that is transmitted to the wheels through the transmission system, causing the car to accelerate.

3. Is there more than one force that accelerates a car?

Yes, in addition to the engine's power, there are other forces that contribute to a car's acceleration, such as friction and air resistance.

4. Does the weight of a car affect its acceleration?

Yes, the weight of a car does affect its acceleration. A heavier car will require more force to accelerate compared to a lighter car.

5. How does the speed of a car affect its acceleration?

The speed of a car does not directly affect its acceleration. However, air resistance and friction increase as the car's speed increases, making it harder to accelerate at higher speeds.

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