# Driving onto a truck while moving?

**URL:** <https://boards.straightdope.com/t/driving-onto-a-truck-while-moving/430090>\
**Category:** Factual Questions\
**Created:** [December 15, 2007, 9:43am UTC](https://boards.straightdope.com/t/driving-onto-a-truck-while-moving/430090 "2007-12-15T09:43:25Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\
**Post date:** [December 16, 2007, 6:52am UTC](https://boards.straightdope.com/t/driving-onto-a-truck-while-moving/430090/21 "2007-12-16T06:52:20Z")

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[QUOTE=wisernow]

Once the wheels are off the road and on the truck, the car will be going at 60 mph relative to the truck.

[/QUOTE]

But it simply doesn’t work that way and assuming it does makes the question meaningless. Once on the truck the car is travelling 3 mph relative to the truck and the wheels give a screech and squeal and slow down. Most likely if you didn’t engage the clutch you’d stall the engine.

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**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\
**Post date:** [December 16, 2007, 8:51am UTC](https://boards.straightdope.com/t/driving-onto-a-truck-while-moving/430090/22 "2007-12-16T08:51:35Z")

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[QUOTE=Szlater]  
Get the wheels in line, get the wheels in line with it and then slam yer brakes on or we’ll be in the cabin!  
[/QUOTE]  
You were only supposed to blow the bloody doors off!

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**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\
**Post date:** [December 16, 2007, 3:50pm UTC](https://boards.straightdope.com/t/driving-onto-a-truck-while-moving/430090/23 "2007-12-16T15:50:07Z")

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[QUOTE=wisernow]  
…Once the wheels are off the road and on the truck, the car will be going at 60 mph relative to the truck.

Sorry if I did not make that clear but I was assuming theoretical conditions…  
[/QUOTE]

No it won’t. If the truck’s speed relative to the ground is 60 mph, and the car’s speed relative to the ground is 62 mph, then immediately before the drive wheels hit the ramp, the car is going 2 mph relative to the truck. Immediately after the drive wheels hit the ramp, the car is still going 2 mph relative to the truck, unless you think that the car can instantly accelerate from 62 mph to 122 mph (relative to the ground) at the instant the drive wheels hit the ramp.

It doesn’t matter if you are assuming “theoretical conditions” or not. You can’t change an object’s velocity instantaneously.

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