So I only took one physics class and never had to do it again, so I have no clue how to think of this. But doesnt a heavier car need more force to bring it + the passengers up to velocity than a lighter vehicle?
If that’s the case and that car crashed, then I would figure the passengers would experience more force going the opposite direction than passengers in the lighter vehicle. That seems like it’d be more dangerous, even though both sets of passengers travelled at the same speed. Am I off base?
The amount of force you experience has nothing to do with the vehicle you’re in, but the acceleration (positive or negative) you experience. In the case of a brake check, the only factors are starting speed, ending speed, and time. It doesn’t matter if you’re increasing speed (positive acceleration) or slowing down (negative acceleration), the total force will be the same (just different directions).
Here are some formulas:
acceleration = change in velocity / change in time
force = mass * acceleration
In this case, the mass is your mass, since you’re the one experiencing the acceleration.
If you’re riding a bicycle at 15mph and slam on the brakes and stop in 10 feet, you’ll feel exactly the same force as being in a massive truck going 15mph and stop in 10 feet.
The momentum matters when you hit something. A large truck has a lot more momentum than a small car. If it hits something it needs proportionally more force to stop it. Since forces are equal and opposite, that means the hit object has to absorb more force. Basically thing of the difference between someone dropping a marble on your head from a balcony to doing the same with a bowling ball. It’s the same with a child hit by a vehicle.
For passengers, only their mass matters. Whether you’re in a car, a truck, a train or an ocean liner, all that matters is the person’s mass and the rate of change.
They actually did something similar with a bus (the large long distance type) when I was in school. Hard brake at walking speed, pretty brutal. IIRC the lesson was to brace against the back of the seat in front of you when there’s an imminent impact/brake event, though of course you usually don’t know beforehand.
When I was doing my driving licence, here it’s mandatory to visit a a slick course before you get your licence. In summer it’s soap and oil or in the winter its ice and water.
Anyway, they had this tiny rig. A car seat, but it’s on a rail, but the rail is only some 1m-1.5m (3-5ft) long, and on like a 5-15° angle, but it simulates a dead stop at like 10-20km/h or smth kinda low. And even that was pretty brutal.
Having seen some videos of North Americans (sans some Alaskans and Canadians) driving in snow, I wholeheartedly agree.
This is gonna come off as racist and sexist, but anyway, the day I was on the track, during winter, there was three of us in the car + the teacher. Me, my mate and a muslim woman who hadn’t lived in Finland for too long, and was from a theocratic and patriarchic society. When it was her turn, and the teacher eventually pulled the handbrake just to simulate her losing control… she let go of the wheel, placed her hands on her eyes and started screaming. But she got over it by the end of the day, so…
Oof. I feel for her. That fight/flight/freeze response can be really hard to override, especially given her background.
I taught myself how to drive in the snow pretty soon after I got my license, in a 1991 FJ80 Land Cruiser with zero electronic aids. I figured out how to drift that pig through the whole church parking lot 😂, but being able to do that on my own was hugely beneficial to where I can now make my FWD cars perform better in the snow than most drivers here with 4WD. I just turn off traction control if it’s too hairy… Sometimes you need that wheelspin.
Man, you can do that at 5 MPH and get a similar reaction. A few thousand pounds of car moving at 5MPH carries way more momentum than people realize.
Edit: 5 MPH is a brisk walk. If you’ve run into a lamppost or a tree during a brisk walk, then you should understand what I mean.
The weight of the car has no impact (excuse the pun) on the momentum of its passengers.
So I only took one physics class and never had to do it again, so I have no clue how to think of this. But doesnt a heavier car need more force to bring it + the passengers up to velocity than a lighter vehicle?
If that’s the case and that car crashed, then I would figure the passengers would experience more force going the opposite direction than passengers in the lighter vehicle. That seems like it’d be more dangerous, even though both sets of passengers travelled at the same speed. Am I off base?
Yes, you’re off base.
The amount of force you experience has nothing to do with the vehicle you’re in, but the acceleration (positive or negative) you experience. In the case of a brake check, the only factors are starting speed, ending speed, and time. It doesn’t matter if you’re increasing speed (positive acceleration) or slowing down (negative acceleration), the total force will be the same (just different directions).
Here are some formulas:
In this case, the mass is your mass, since you’re the one experiencing the acceleration.
If you’re riding a bicycle at 15mph and slam on the brakes and stop in 10 feet, you’ll feel exactly the same force as being in a massive truck going 15mph and stop in 10 feet.
The momentum matters when you hit something. A large truck has a lot more momentum than a small car. If it hits something it needs proportionally more force to stop it. Since forces are equal and opposite, that means the hit object has to absorb more force. Basically thing of the difference between someone dropping a marble on your head from a balcony to doing the same with a bowling ball. It’s the same with a child hit by a vehicle.
For passengers, only their mass matters. Whether you’re in a car, a truck, a train or an ocean liner, all that matters is the person’s mass and the rate of change.
If you have toy car Lamborghini that has the same 0-60 and speed of an actual Lamborghini, does it even matter?
I once asked my physics professor if I would feel more force when breaking on a bus compared to a regular car and I believe the answer was no.
“Weight has nothing to do with it!”
Great example of the difference between the ability to read and comprehending what you read.
weight of the car
They actually did something similar with a bus (the large long distance type) when I was in school. Hard brake at walking speed, pretty brutal. IIRC the lesson was to brace against the back of the seat in front of you when there’s an imminent impact/brake event, though of course you usually don’t know beforehand.
When I was doing my driving licence, here it’s mandatory to visit a a slick course before you get your licence. In summer it’s soap and oil or in the winter its ice and water.
Anyway, they had this tiny rig. A car seat, but it’s on a rail, but the rail is only some 1m-1.5m (3-5ft) long, and on like a 5-15° angle, but it simulates a dead stop at like 10-20km/h or smth kinda low. And even that was pretty brutal.
That sounds wonderful. With the amount of total morons on the road today, this needs to be implemented in every US state.
Having seen some videos of North Americans (sans some Alaskans and Canadians) driving in snow, I wholeheartedly agree.
This is gonna come off as racist and sexist, but anyway, the day I was on the track, during winter, there was three of us in the car + the teacher. Me, my mate and a muslim woman who hadn’t lived in Finland for too long, and was from a theocratic and patriarchic society. When it was her turn, and the teacher eventually pulled the handbrake just to simulate her losing control… she let go of the wheel, placed her hands on her eyes and started screaming. But she got over it by the end of the day, so…
Oof. I feel for her. That fight/flight/freeze response can be really hard to override, especially given her background.
I taught myself how to drive in the snow pretty soon after I got my license, in a 1991 FJ80 Land Cruiser with zero electronic aids. I figured out how to drift that pig through the whole church parking lot 😂, but being able to do that on my own was hugely beneficial to where I can now make my FWD cars perform better in the snow than most drivers here with 4WD. I just turn off traction control if it’s too hairy… Sometimes you need that wheelspin.
unless you find yourself between the car and a stationary object, the few thousand pounds of car has no influence here.
I do agree though that a human body traveling at 5MPH do carry way more momentum than many realize.