Okay the Question is: A crime scene investigator assesses the aftermath of a car crash on the 401 (speed limit = 100 km/h). The skid mark on the pavement is 8.2 m long and the negative acceleration for a skidding car is known to be 85 m/s^2. Based on this information, can the investigator give the driver a speeding ticket?
So for this i got:
Acceleration= 85 m/s
Delta d= 8.2 m
v2=0
and I have to find v1 right?
But what formulas do i use? and what do i do? Please help thanks!
So for this i got:
Acceleration= 85 m/s
Delta d= 8.2 m
v2=0
and I have to find v1 right?
But what formulas do i use? and what do i do? Please help thanks!
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First off, I think you live in the Toronto area. I know that highway too! Also, acceleration is metres per second squared (m/s^2) ; not just m/s
Yes, you're looking for v1. You might have learned the 5 kinematic equations.
Use:
v2^2=v1^2+2ad (use this one because times is not given, and it's not required)
Re-arrange so that V1 is on a side of it's own.
v2^2 - 2ad =v1^2
Sub in numbers
(0)^2 - 2(-85m/s^2)(8.2m) = v1^2 (acceleration is negative)
1394m/s = v1^2
Square root both sides
37.34 m/s=v1
Now we have v1 but I assume you want it in km/h instead of m/s
So divide the answer by 1000 to get it into km/s
37.34/1000= 0.03734km/s
Multiple by 360 ( 60s = 1 minute, 60mins = 1 hr or 60x60)
13.44km/hr
^ That looks pretty slow to me ( i could have done my calculations wrong). I believe the car was going 13.44km/hr when it began to skid.
So no, based on this information the investigator can not give the driver a speeding ticket.
I rechecked my work and it seems okay but I'm also tired right now so maybe it's wrong.
Yes, you're looking for v1. You might have learned the 5 kinematic equations.
Use:
v2^2=v1^2+2ad (use this one because times is not given, and it's not required)
Re-arrange so that V1 is on a side of it's own.
v2^2 - 2ad =v1^2
Sub in numbers
(0)^2 - 2(-85m/s^2)(8.2m) = v1^2 (acceleration is negative)
1394m/s = v1^2
Square root both sides
37.34 m/s=v1
Now we have v1 but I assume you want it in km/h instead of m/s
So divide the answer by 1000 to get it into km/s
37.34/1000= 0.03734km/s
Multiple by 360 ( 60s = 1 minute, 60mins = 1 hr or 60x60)
13.44km/hr
^ That looks pretty slow to me ( i could have done my calculations wrong). I believe the car was going 13.44km/hr when it began to skid.
So no, based on this information the investigator can not give the driver a speeding ticket.
I rechecked my work and it seems okay but I'm also tired right now so maybe it's wrong.