Car Treadmill: Driving 40mph w/ G Force Shock?

  • Context: Undergrad 
  • Thread starter Thread starter bunion
  • Start date Start date
  • Tags Tags
    Car
Click For Summary

Discussion Overview

The discussion explores the hypothetical scenario of a car driving onto a giant treadmill moving at 40mph, examining the effects on speed, g forces, and vehicle dynamics during the transition. It includes considerations of acceleration, deceleration, and the mechanics of driving on a treadmill, with some references to popular media and personal experiences.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that driving onto the treadmill at 40mph would result in a combined speed of 80mph relative to the ground, leading to noticeable g forces during the transition.
  • Another participant notes that if the treadmill slows down, the car would also decelerate, experiencing additional g forces until it reaches 40mph again.
  • A different viewpoint indicates that the car would transition at 0mph relative to the treadmill, potentially causing the engine to stop unless the driver intervenes.
  • One participant clarifies that if the treadmill runs in the opposite direction, the car's wheels would spin up to 80mph almost instantly, leading to a slow deceleration.
  • References to a Mythbusters episode are made, where a car transitioned onto a ramp without noticeable jerking, suggesting that the engine did not die immediately.
  • Another participant questions whether a manual transmission would require a quick downshift during such a transition.
  • A speculative question is raised about whether a car with wings could take off in this scenario, which is met with a counterclaim that cars cannot fly.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the dynamics of the car on the treadmill, with no consensus on the effects of g forces or the mechanics involved. Some agree on certain aspects of vehicle behavior, while others present competing interpretations of the scenario.

Contextual Notes

Assumptions about the treadmill's speed, the car's engine behavior, and the specifics of the transition are not fully resolved, leaving open questions about the dynamics involved.

bunion
Messages
6
Reaction score
0
What would happen if you drove a car at 40mph along a road onto a giant car treadmill running at 40mph? Would you experience any noticeable g force shock? If the car was on the treadmill and the treadmill started slowing down what would happen to its speed when it left the treadmill and rejoined a road?
 
Physics news on Phys.org
As soon as you are aboard the treadmill, you'll be moving at 80 mph wrt ground, because you still have your engines on at the same power. Then definitely there was accn and thus g forces during the time you crossed over.

If the treadmill starts to slow down, the car will also slow down and so again g forces. At the time of rejoining the road, the speed of the treadmill has not been specified. Assuming it's still moving, then the car will experience a braking force until it's going at 40 mph again, and thus again some g forces during the time until it has slowed down to 40 mph.

Whether all these g forces were "noticeable" or not depend on the times involved and will require more precise calculations with additional information
 
Last edited:
The car would transition onto the treadmill at 40mph relative to ground, 0mph relative to the treadmill, and the engine would most likely stop if the driver didn't use the clutch or shift into neutral as the car transitioned onto the tread mill. Once on the tread mill, the car could be accelerated as if it were moving at 0mph, since the point of application of force at the rear tires is now the treadmill.
 
Sorry forgot to say the treadmill would be running in the opposite direction
 
If the treadmill were going in the opposite direction so the combined speed was 80 mph, the car's wheels would spin up to 80 mph almost instantly and the car would then decelerate slowly to just a few mph with respect to the ground and, say, 45 mph with respect to the treadmill (if the driver applied no extra gas).
 
by reading all your posts i can see that you guys understand quite a bit about physics.
As i haven't studied it before; but will soon, would u guys have any tips for me to get like an extra boost.. any easier way to understand physics?
 
Mythbusters dispelled (or confirmed, depending on your PoV) this myth on one ep. Pretty much, anyway.

They drove a car from highway speed onto a ramp behind a truck.

The wheels adjusted instantly, and there was almost no noticeable jerking in the car.

Of note: the engine did NOT die as soon as the wheels stopped. They were able to drive the car up the ramp into the truck.
 
DaveC426913 said:
Mythbusters dispelled (or confirmed, depending on your PoV) this myth on one ep. Pretty much, anyway.

They drove a car from highway speed onto a ramp behind a truck.

The wheels adjusted instantly, and there was almost no noticeable jerking in the car.

Of note: the engine did NOT die as soon as the wheels stopped. They were able to drive the car up the ramp into the truck.
Cool! I've fantasized about doing this many times. I'll bet they were driving an auto. transmission car, though. With a stick shift, you'd have to do a quick downshift to accommodate the sudden decrease in wheel speed, wouldn't you? Of course, I drive a front wheel drive car - I guess it doesn't matter with RWD, does it?
 
belliott4488 said:
Cool! I've fantasized about doing this many times. I'll bet they were driving an auto. transmission car, though. With a stick shift, you'd have to do a quick downshift to accommodate the sudden decrease in wheel speed, wouldn't you? Of course, I drive a front wheel drive car - I guess it doesn't matter with RWD, does it?
I think they drove the same model from Night Rider - a 1982 Pontiac Firebird Trans Am.
 
  • #10
Thanks for the help everyone
 
  • #11
i needed help too..
 
  • #12
If the car had wings would it take off?
 

Similar threads

Undergrad What forces oppose a car's motion when braking?
  • · Replies 8 ·
Replies
8
Views
5K
Graduate Inertia Translation Rotation Moments And Couples, car on accelerating Treadmill
  • · Replies 19 ·
Replies
19
Views
6K
High School Opening a car door at a high speed
  • · Replies 16 ·
Replies
16
Views
7K
Undergrad Is a car's top speed the same on a wet road?
  • · Replies 26 ·
Replies
26
Views
7K
Undergrad Calculate approximately G-force applied on Car shock absorber
  • · Replies 1 ·
Replies
1
Views
5K
Undergrad Can an object maintain uniform motion without any external force?
  • · Replies 66 ·
3
Replies
66
Views
6K
Undergrad Force of car at 40mph is equivalent to bowling ball at ?
  • · Replies 2 ·
Replies
2
Views
4K
Undergrad What are the effects of Buoyancy & G-force combined in this scenario?
  • · Replies 9 ·
Replies
9
Views
3K
Undergrad Name of the forces caused while driving a car
  • · Replies 5 ·
Replies
5
Views
1K
Undergrad What is the direction of friction
  • · Replies 1 ·
Replies
1
Views
6K