Finding speed when given deceleration and distance?

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SUMMARY

The discussion centers on solving a physics problem involving a car that leaves skid marks of 80 meters while decelerating at 7.00 m/s². The key formula to use is the SUVAT equation: v² - u² = 2as, where 'v' is the final velocity (0 m/s when the car stops), 'u' is the initial velocity, 'a' is the acceleration (in this case, -7.00 m/s²), and 's' is the distance (80 m). By rearranging the formula, users can calculate the initial speed of the car just before braking.

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  • Understanding of SUVAT equations in physics
  • Basic knowledge of kinematics
  • Ability to manipulate algebraic equations
  • Familiarity with units of measurement (meters, seconds)
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  • Study the derivation and applications of SUVAT equations
  • Practice solving kinematics problems involving deceleration
  • Explore real-world applications of motion equations in automotive safety
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Mady Hernandez
Hi!
I have this homework problem that has me completely stumped. Any help is greatly appreciated!

In coming to a stop, a car leaves skid marks 80m long on the highway. Assuming a deceleration of 7.00m/s2, estimate the speed of the car just before braking.

I just can't figure out what formula to use. If you can help, thank you so much!
 
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Mady Hernandez said:
Hi!
I have this homework problem that has me completely stumped. Any help is greatly appreciated!

In coming to a stop, a car leaves skid marks 80m long on the highway. Assuming a deceleration of 7.00m/s2, estimate the speed of the car just before braking.

I just can't figure out what formula to use. If you can help, thank you so much!
You can solve it using v^2 -u^2=2as.
Since you decelerating, put in a=-7.
You need to find u here
 

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