What is the net force on the car?

In summary, at a certain instant of time, a 1200 kg car traveling along a curve 250 m in radius is moving at a speed of 10 m/s but is slowing down at a rate of 2 m/s2. The total frictional force is equal to mv^2/R - 2m, taking into account both the tangential and radial components of acceleration.
  • #1
pillanoid
10
0

Homework Statement


At a certain instant of time, a 1200 kg car traveling along a curve 250 m in radius is moving at a speed of 10 m/s but is slowing down at a rate of 2 m/s2. Ignoring air friction, what is the total static friction force on the car as a fraction of its weight at that instant?


Homework Equations


Fc = mv2/R
Ff = [tex]\mu[/tex]FN = [tex]\mu[/tex]mg


The Attempt at a Solution


I have an idea at how to attempt this...
mv2/R = Ff
(since the centripetal force is provided by the frictional force)
but I need clarification: I see it that the frictional force and the force due to the acceleration (deceleration) of the car act perpendicular to each other and therefore on different axes.
How would you account for this force due to deceleration in calculating the centripetal force? Is this just a matter of calculating the speed of the car at that instant, in which case the deceleration doesn't matter?
 
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  • #2
Careful. Friction provides all the force accelerating the car, not just the centripetal force. There's both a tangential and a centripetal component.
 
  • #3
Ah, okay. So the total frictional force is equal to mv^2/R - 2m = -1.6m?
 
  • #4
Unfortunately it's not that simple.

The accelerations are vectors and they are not acting in the same direction.

Figure the sum of the vectors first because the slowing is tangential and the centripetal is radial.
 

Related to What is the net force on the car?

1. How do net forces affect a car on a turn?

Net forces play a crucial role in determining the motion of a car on a turn. When a car is turning, there are two main forces acting on it: the centripetal force, which pulls the car towards the center of the turn, and the centrifugal force, which pushes the car away from the center. The net force is the sum of these two forces and determines the direction and speed of the car.

2. How does the speed of a car affect net forces on a turn?

The speed of a car directly affects the net forces on a turn. The faster the car is moving, the greater the centrifugal force will be, which means the net force will also be greater. This is why it is important to slow down when making a turn in order to maintain control and prevent the car from sliding or spinning out.

3. What role does the weight of a car play in net forces on a turn?

The weight of a car can also impact net forces on a turn. A heavier car will have a greater gravitational force, which can affect the balance of the car and its ability to make turns smoothly. This is why sports cars, which are designed to have a lower weight, are often able to make sharper turns at higher speeds.

4. How does the shape of a turn affect net forces on a car?

The shape of a turn can greatly impact the net forces on a car. If a turn is sharp and has a small radius, the centripetal force required to make the turn will be greater, resulting in a higher net force. On the other hand, if a turn has a larger radius, the centripetal force needed will be smaller, resulting in a lower net force.

5. What are some factors that can affect the stability of a car on a turn?

Aside from net forces, there are several other factors that can impact the stability of a car on a turn. These include the condition of the road, the type of tires on the car, and the weight distribution within the car. Additionally, driver skill and reaction time can also play a role in maintaining stability while making a turn.

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