Force of acceleration in car?

In summary: Would it be accurate to say that the gear wheel does not actually spin faster, as the mechanism by which the car is propelled is quite mysterious to me?The gear wheel does not actually spin faster--the mechanism by which the car is propelled is quite mysterious to you.
  • #1
pivoxa15
2,255
1

Homework Statement


Newton's Second Law of motion states that there must be a net force for a body to have an acceleration and that the acceleration is in the direction of the net force. When you push down on the accelerator of a car it accelerates forward. What force is exerted on the car to accelerate it?


Homework Equations


none


The Attempt at a Solution


The accelerator triggers a device in the car which then triggers something that accelerates the car by exerting a force to something. Does the gear wheel spin faster? What I don't understand is the internal workings of the car. This question may not ask it directly but for a complete answer it would be good to incoprate it in or at least mention aspects of the car.
 
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  • #2
You don't need to know the inner workings of a car to answer this question. Hint: An external force is required to accelerate an object.
 
  • #3
pivoxa15 said:

Homework Statement


Newton's Second Law of motion states that there must be a net force for a body to have an acceleration and that the acceleration is in the direction of the net force. When you push down on the accelerator of a car it accelerates forward. What force is exerted on the car to accelerate it?


Homework Equations


none


The Attempt at a Solution


The accelerator triggers a device in the car which then triggers something that accelerates the car by exerting a force to something. Does the gear wheel spin faster? What I don't understand is the internal workings of the car. This question may not ask it directly but for a complete answer it would be good to incoprate it in or at least mention aspects of the car.
I'm no car mechanic, so the internal workings of a car are beyond me. But as far as what the net force is that accelerates car, does a car accelerate forward , with your foot on the pedal and the car in gear, if it were on a very icy slippery road, especially with an uphill slope? Why or why not?
 
  • #4
Doc Al said:
You don't need to know the inner workings of a car to answer this question. Hint: An external force is required to accelerate an object.

So you are saying the (external) force of my foot accelerates the car. What about the 'literal' force that is accelerating the car? i.e. what makes the gear wheels turn faster?

Out of interest, I like to know the chain reaction i.e. foot on accelerator => ... ... =>observed acceleration of car
 
Last edited:
  • #5
Think about what PhantomJay said about a slippery road. No, the force of your foot does not accelerate the car--that's silly. Think external! something outside the car literally pushes it.
 
  • #6
When you press the accelerator, you increase the amount of fuel injected into the engine's cylinders. The burning of the fuel creates gaseous pressure, and the pressure pushes on the pistons. The pistons then push on the crankshaft, resulting in a torque that causes it to spin faster. The crankshaft is ultimately connected to the wheels, and the wheels experiences a torque which causes them to spin faster. The friction of the tires against the pavement resists the torque, and the car experiences a force, equal and opposite that of the friction, that propels it forward.

- Warren
 
  • #7
just to clarify what he said, friction is the force that I was trying to get at. Keep in mind that Earth has a huge mass--if it did not, a car would go forward and Earth would go backwards at the same time.
 
  • #8
pivoxa15 said:
So you are saying the (external) force of my foot accelerates the car. What about the 'literal' force that is accelerating the car? i.e. what makes the gear wheels turn faster?
The force of your foot is not an external force--you (and your foot) are part of the system being accelerated. As has been explained, the external force that accelerates the car is the friction force of the road on the tires--take away that friction and you can step on the gas all you like and get nowhere. (Of course, how to arrange things to create that external friction force is the trick!)

Out of interest, I like to know the chain reaction i.e. foot on accelerator => ... ... =>observed acceleration of car
Warren explained that perfectly.
 
  • #9
Ahh, friction is the external force, that makes sense.

thanks chroot for the explanation of the inner workings of the car. It's amazing how well designed the modern car is. There is an almost instaneous acceleration of the car after pushing down the accelerator.
 

1. What is force of acceleration in a car?

The force of acceleration in a car is the amount of force required to increase the car's velocity. It is measured in Newtons (N).

2. How is force of acceleration calculated in a car?

Force of acceleration in a car is calculated by dividing the car's mass by the time it takes to reach a certain velocity. This is known as Newton's second law of motion, which states that force is equal to mass times acceleration (F=ma).

3. What factors affect the force of acceleration in a car?

The force of acceleration in a car can be affected by several factors, such as the car's weight, engine power, and aerodynamics. Other external factors like friction, air resistance, and road conditions can also impact the force of acceleration.

4. How does the force of acceleration impact the car's performance?

The force of acceleration directly affects the car's performance, as it determines how quickly the car can reach a certain speed. A higher force of acceleration means the car can accelerate faster, while a lower force of acceleration may result in a longer acceleration time.

5. Can the force of acceleration be increased in a car?

Yes, the force of acceleration in a car can be increased by increasing the engine power or reducing the car's weight. This can be achieved through modifications or upgrades to the engine, exhaust system, and other components of the car.

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