Converting engine power into a force

• batmx3man
In summary, the conversation discusses how to accurately calculate the top speed of a car using power, mass, drag, and friction. The speaker suggests using the formula power = force x speed to calculate horsepower, taking into consideration drivetrain and rolling friction losses. They also mention the need to estimate aerodynamic drag and how to convert torque into force for the driven wheel.

batmx3man

I am wanting to accurately calculate the top speed of a car (using it's power, mass, drag, and friction). I started by suming up the forces, but I cannot think of a way to translate the engines power into the force pushing the car forward.

power is energy/time. energy or work, is force*distance. so instantaneous power is force*distance/time, which is force*velocity.

Prob. not enough detail. How do I convert the torque of power the engine is sending to the wheel into a force. I thought about t=rF => F=t/r with r being the wheel radius, but that doesn't make sense. So, I need a way to translate the torque/ power the engine is sending to the wheel into a force that the wheels are exerting (sp?) against the ground to move the car forward. Maybe I am going about this problem in the wrong way idk.

Power = force times speed.

In English units to calculate horsepower given force and speed:

power/hp = force (lbs) x speed (mph) / 375 (conversion factor).

You can ignore the gearing factor, since it's assumed that you gear the car so peak power occurs at top speed, so the rpm, torques, ... don't need to be known. You'll need to estimate drivetrain and rolling friction losses and reduce the peak power by this amount, usually 15% loss is a good estimate for cars with manual trannys. The next problem is calculating aerodynamic drag, which will be related to cross sectional area times coefficient of drag times speed2.

How do I convert the torque of power the engine is sending to the wheel into a force?
Driven wheel force = wheel torque divided by effective radius of tire. Wheel torque = engine torque times overall gear ratio (times effeciency factor, 85% is a reasonable esitmate).

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1. How is engine power converted into a force?

Engine power is converted into a force through the principle of conversion of energy. The engine produces power, which is then used to turn a crankshaft, which in turn produces rotational force. This rotational force is then transmitted to the wheels of a vehicle, allowing it to move forward.

2. What is the role of the transmission in converting engine power into force?

The transmission plays a crucial role in converting engine power into force. It uses gears to adjust the speed and torque of the output shaft, allowing the engine to operate at its most efficient RPM range while providing enough force to move the vehicle.

3. Does the type of engine affect the conversion of power into force?

Yes, the type of engine can significantly affect the conversion of power into force. For example, a diesel engine produces more torque at lower RPMs, making it better suited for heavy-duty applications, while a gasoline engine produces more power at higher RPMs, making it better for high-speed applications.

4. How does the amount of engine power affect the force generated?

The amount of engine power directly affects the force generated. Generally, the more power an engine produces, the more force it can generate. However, other factors such as the weight and efficiency of the vehicle also play a role in determining the overall force produced.

5. Can engine power be converted into other forms of energy besides force?

Yes, engine power can be converted into other forms of energy, such as electricity. This is commonly seen in hybrid vehicles, where the engine powers a generator that charges the battery, which in turn powers an electric motor to move the vehicle. In this case, the engine power is indirectly converted into force through the electric motor.