Question if a driver would be thrown from a vehicle?

[sbeer6er]

If a driver of a truck weighing 46,000lbs going 0mph was hit head on by a car weighing 4000lbs going roughly 60mph would the unseat belted truck driver be thrown from his truck?

 

[chrisbaird]

It depends on the strength of the windshield, the driver's weight, and if he hit the steering wheel along the way. He would definitely be jolted. If we assume an inelastic collision, then the conservation of momentum tells us: p_truck + p_car = p_after. We know that p_truck = 0 because it is not moving to start so p_car = p_after. The value of p_car is just (4000 lbs/g)x(60 mph) and the value of p_after is (50,000 lbs/g)x v so v = 4.8 mph. Technically, the truck driver has no seat belt holding him to the car, so he remains stationary at 0 mph and the windshield/steering wheel hits him at 4.8 mph. This is probably not fast enough to break the glass. This is equivalent to briskly walking into a glass window.

 

[pallidin]

It depends on the strength of the windshield, the driver's weight, and if he hit the steering wheel along the way. He would definitely be jolted. If we assume an inelastic collision, then the conservation of momentum tells us: p_truck + p_car = p_after. We know that p_truck = 0 because it is not moving to start so p_car = p_after. The value of p_car is just (4000 lbs/g)x(60 mph) and the value of p_after is (50,000 lbs/g)x v so v = 4.8 mph. Technically, the truck driver has no seat belt holding him to the car, so he remains stationary at 0 mph and the windshield/steering wheel hits him at 4.8 mph. This is probably not fast enough to break the glass. This is equivalent to briskly walking into a glass window.

Would your equation suggest that this scenario is "roughly" equivalent to the 46,000 lb truck(with an unbealted driver) hitting an immovable wall at 4.8 mph?
If so, I see your logic.

 

[AlephZero]

It depends what the truck driver was doing at the time.

If he/she was standing up in the cab and the truck brakes were off, quite likely he/she would at least fall over, and possibly fall out of an open door.

I once "accidentally" took part in a similar experiment, the main difference being that several people were standing up in a boat traveling at about 5 mph which collided with the stone pier of a bridge. All the people who didn't see that the collision was going to happen went for an unscheduled swim (including me!)

Would your equation suggest that this scenario is "roughly" equivalent to the 46,000 lb truck(with an unbealted driver) hitting an immovable wall at 4.8 mph?

Only if the truck's brakes were off, which may not be the case if the truck was stationary.

 

[sbeer6er]

Would your equation suggest that this scenario is "roughly" equivalent to the 46,000 lb truck(with an unbealted driver) hitting an immovable wall at 4.8 mph?
If so, I see your logic.

depends how thick and or strong the walls is. lol thank you...

 

[sbeer6er]

It depends on the strength of the windshield, the driver's weight, and if he hit the steering wheel along the way. He would definitely be jolted. If we assume an inelastic collision, then the conservation of momentum tells us: p_truck + p_car = p_after. We know that p_truck = 0 because it is not moving to start so p_car = p_after. The value of p_car is just (4000 lbs/g)x(60 mph) and the value of p_after is (50,000 lbs/g)x v so v = 4.8 mph. Technically, the truck driver has no seat belt holding him to the car, so he remains stationary at 0 mph and the windshield/steering wheel hits him at 4.8 mph. This is probably not fast enough to break the glass. This is equivalent to briskly walking into a glass window.

wow thank you, great answer... I'll add in that he was holding the brakes and this answers my question.