The driver pushes the accelerator pedal as far down as possible. The car does not accelerate above a certain maximum speed. Explain the reason for this in terms of the forces acting on the car.
forces:
road pushes forward on tires, there is a limit to how hard depending on torque from drive shaft.
wind pushes back on vehicle, force increases as speed increases
so
net force forward = Froad - Fwind
a = (Froad - Fwind) / mass
when Froad = Fwind, a is zero
if a is 0, v is constant
Thanks Damon!!
When the driver pushes the accelerator pedal as far down as possible, it increases the power supplied to the car's engine. As a result, the engine generates more torque, which is transferred to the wheels through the transmission system. However, there are several forces that act on the car, which limit its acceleration and prevent it from reaching a certain maximum speed. These forces include:
1. Air Resistance: As the car moves forward, it encounters resistance from the air, known as drag or air resistance. At lower speeds, the air resistance is relatively low, but as the car accelerates, the force of air resistance increases. Eventually, a point is reached where the air resistance force becomes equal to or greater than the engine's accelerating force. This opposition from air resistance prevents the car from accelerating further.
2. Rolling Resistance: Another force that opposes the car's motion is rolling resistance, which occurs between the tires and the road surface. As the car accelerates, the tires deform slightly, causing a frictional force that acts in the opposite direction to the car's motion. The faster the car tries to go, the greater the rolling resistance force becomes. At a certain speed, this force matches the engine's accelerating force, limiting further acceleration.
3. Gravitational Force: Gravity also acts on the car, pulling it downward. While it doesn't directly oppose the car's motion, it affects how the tires grip the road surface. When the car reaches a high speed, the downward force due to gravity increases, causing the tires to lose traction and reducing the available acceleration.
4. Mechanical Limitations: The car itself has mechanical limitations that can prevent further acceleration. These limitations can include the engine's power output, the capability of the transmission system, or the limited grip of the tires on the road surface. Once the car reaches a certain speed, these limitations may prevent the engine from generating enough power or the tires from maintaining sufficient traction to continue accelerating.
Overall, the forces of air resistance, rolling resistance, gravitational force, and mechanical limitations combine to restrict the car's acceleration above a certain maximum speed, even when the driver fully presses the accelerator pedal.
The reason why the car does not accelerate beyond a certain maximum speed, even when the driver pushes the accelerator pedal as far down as possible, can be explained by considering the forces acting on the car.
When the driver pushes the accelerator pedal, the car's engine generates power, which is transferred to the wheels through the transmission system. As a result of this power transfer, a forward force is applied to the car's tires, known as the driving force or tractive force.
However, several opposing forces come into play and affect the car's acceleration. The main forces that restrict the car's acceleration are:
1. Drag Force: As the car moves forward, it encounters air resistance, which creates a drag force that opposes the car's motion. The faster the car drives, the greater the drag force becomes. At high speeds, the drag force can become significant and ultimately limit the car's acceleration.
2. Rolling Resistance: Another force acting against the car's motion is rolling resistance, generated by the interaction between the tires and the road surface. This force depends on various factors such as tire design, road condition, and tire pressure. Rolling resistance increases with speed and consumes a portion of the engine's power, reducing the available power for acceleration.
3. Frictional Forces: When the car's tires grip the road surface, frictional forces come into play. While these forces are necessary for propulsion, excessive wheel slip or too little friction (e.g., on icy roads) can impede acceleration.
4. Mechanical Limitations: The car's design, mechanical components, and powertrain play a role in limiting its top speed. Factors such as the engine power, gear ratios, aerodynamics, tire grip, and other mechanical constraints determine the car's maximum achievable speed.
Considering these forces, there comes a point where the driving force from the engine is balanced by the combined effect of drag force, rolling resistance, and other opposing forces. This equilibrium is reached at the car's maximum speed, where all the forces acting against acceleration cancel out the driving force, preventing the car from accelerating further.
To summarize, the car does not accelerate beyond a certain maximum speed due to the combined effect of drag force, rolling resistance, frictional forces, and mechanical limitations, which counteract the driving force provided by the engine. These forces reach an equilibrium, limiting the car's acceleration.