# Collision and impact

#### Just_enough

1. Homework Statement
A car moving at 30 m/s has a collision and comes to rest in 0.1 seconds. The driver, ClarkGriswold, is brought to rest by an air bag in 0.13s. The driver has a mass of 50 kg.
1) What average force is exerted by the air bag on the driver ?
3) How far does the driver travel while stopping?
4) Two suitcases fly off the roof of the carmoving at 12 m/s relative to the groundand the lid of one pops open, pushingthem apart. The opened suitcase, with amass of 20 kg, is moving at 6 m/s afterthey separate. If the second suitcase hasa mass of 15 kg, what is its velocityafter they separate? https://gyazo.com/59d8533684d27020728eb27ae61cf85d.jpg [Broken]

3. The Attempt at a Solution
1) I assume you use impulse = change (f*t=m*change in v)) in momentum to find the force, but my teacher been talking about using energy to solve stuff, so I don't know if I can use energy formula to solve it somehow? also my answer using impulse = change in momentum equation give me 11538.46 N
3) Is it easy as multiplying the speed to the .13s? (30m/s*0.13s)
4) wouldnt the red suitcase continues flying at 12m/s?

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#### TSny

Homework Helper
Gold Member
1) I assume you use impulse = change (f*t=m*change in v)) in momentum to find the force, but my teacher been talking about using energy to solve stuff, so I don't know if I can use energy formula to solve it somehow? also my answer using impulse = change in momentum equation give me 11538.46 N
Using impulse is the way to go. Energy concepts are not useful here. Your answer looks correct, but you have way too many significant figures.
3) Is it easy as multiplying the speed to the .13s? (30m/s*0.13s)
No, the driver does not travel at 30 m/s throughout the 0.13 s time interval.
4) wouldnt the red suitcase continues flying at 12m/s?
Why did the gray suitcase slow down? Was the red suitcase involved? ### Want to reply to this thread?

"Collision and impact"

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