Free Body Diagram of a Car Moving at Constant Speed
Introduction
When a car is moving at constant speed, the net force acting on the car is zero. This means that the forces acting on the car are balanced. The free body diagram of a car moving at constant speed shows all of the forces acting on the car.
Forces Acting on a Car Moving at Constant Speed
The forces acting on a car moving at constant speed are:
* Weight (W): The weight of the car is the force of gravity acting on the car. It is directed downward.
* Normal force (N): The normal force is the force exerted by the road on the car. It is directed upward and perpendicular to the road surface.
* Friction force (f): The friction force is the force that opposes the car’s motion. It is directed opposite to the direction of motion.
* Air resistance (D): Air resistance is the force that opposes the car’s motion through the air. It is directed opposite to the direction of motion.
Free Body Diagram
The free body diagram of a car moving at constant speed is shown below.
[Image of a free body diagram of a car moving at constant speed]
Equilibrium Equations
The equilibrium equations for a car moving at constant speed are:
* ΣF_x = 0: The sum of the forces in the x-direction is zero.
* ΣF_y = 0: The sum of the forces in the y-direction is zero.
These equations can be used to solve for the unknown forces acting on the car.
Example
A car with a mass of 1000 kg is moving at a constant speed of 10 m/s. The coefficient of friction between the car and the road is 0.1. The air resistance coefficient is 0.5.
Calculate the normal force and the friction force acting on the car.
ΣF_x = 0:
f – D = 0
f = D
f = 0.5 * 1000 kg * (10 m/s)^2 = 500 N
ΣF_y = 0:
N – W = 0
N = W = 1000 kg * 9.81 m/s^2 = 9810 N
Therefore, the normal force acting on the car is 9810 N and the friction force acting on the car is 500 N.
Conclusion
The free body diagram of a car moving at constant speed is a useful tool for understanding the forces that act on the car. The equilibrium equations can be used to solve for the unknown forces acting on the car.
