Calculating total kinetic energy of a car at a given velocity

AI Thread Summary
Total kinetic energy of a car includes both translational kinetic energy and rotational kinetic energy (RKE) of the wheels. While RKE may be less significant than translational KE in most cases, it can be important in specific scenarios, such as with old diesel engines where the flywheel's RKE can impact performance at low speeds. Calculating RKE for a solid disk can provide insights into its contribution, especially in unique setups like stationary engines. The discussion also touches on the kinetic energy of pistons, suggesting that various components can influence overall energy calculations. Understanding these factors is crucial for accurate assessments of a vehicle's kinetic energy.
Phunee
Messages
4
Reaction score
0
When calculating the total kinetic energy do i have to take into account the rotational kinetic energy of the wheels?
 
Physics news on Phys.org
Yes. It's kinetic energy so it contributes to the total kinetic energy.
 
Thanks
 
But is the RKE of the wheels significant compared to the translational KE of the car? It might make an instructive exercise to calculate the RKE of e.g. a solid disk of mass M rotating with angular speed ω = v/R where v is the linear speed of the car and R is the radius of the wheel.
 
For some old diesel engines, the RKE of the flywheel could be significant, too. If you ran the engine at full speed, with the car stationary and then lifted the valves and let the clutch in, the car would move forward at 'significant speed', implying that the RKE of the flywheel could be significant at low car speeds.
I can't do that experiment with my 3.5 ton boat because I can only engage drive with the engine on tick over but, as KE is proportional to v2 and the maximum speed is less than 10 km/hr, the flywheel energy must be significant. I must do the sums one day.

They used to quote the instantaneous horse power of traction engines for when you would use the flywheel to provide some high power in bursts.
 
What about the KE of the pistons?
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »
Thread 'Beam on an inclined plane'

Thread 'Beam on an inclined plane'

Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
View full post »

Similar threads

I The proportion of kinetic energy of a rotating rigid body?
Replies
7
Views
1K
B Can energy be decomposed?
Replies
2
Views
1K
I Torque and Rotational Kinetic Energy Relationship
Replies
4
Views
2K
B The physics of flywheel launchers (like tennis ball shooters)
2
Replies
60
Views
4K
B What is the need for the concepts of Work and Energy (KE)?
Replies
8
Views
1K
Why do we add Kinetic and Potential energy?
Replies
3
Views
1K
Energy transformed in a collision
Replies
5
Views
2K
Escape Velocity Question: Why is the final kinetic energy = 0?
Replies
21
Views
5K
I Kinetic Energy derivation assumption?
Replies
11
Views
2K
I Question about Momentum vs. Kinetic Energy vs. Deforming In Collisions
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top