RA_Alg



Crime scene investigators will use a easy equation to figure out how fast a car was traveling based on the distance of the skid mark left behind, and the percent of friction the surface has, all multiplied by 30 square root. s=√30fd. s=speed, f=friction of surface, d=distance. media type="youtube" key="krMx_ELwC0M" width="425" height="350" align="center"

7. **36.74 mph. s=**√30fd. Of which the speed is still unknown. The friction of an iced road would be 0.15 and the distance of the skid mark would be 300 feet. Taken the equation, first we would insert the numbers into friction and distance. Multiply the numbers and you would get **speed**=√1350. You can either break down the square root to 15√6 or just enter it into the calculator, giving you the speed limit of the car before the accident, which would be 36.74 mph. 8. **56.28 mph.** first take the equation, and enter the numbers, of which are 0.8 for F and 132 for D. After Multiplying the numbers you will get 3168 under the square root. After you enter the numbers you will get 56.28 mph, after rounding to the nearest tenth. media type="youtube" key="YB_JCUw9SoU" width="425" height="350" 9. **84.38 feet skid.** For this question we were to find the distance of a car skid, proposed that the driver was only going 45, in a court case. The process will be slightly the same. Enter the number you will get 45=√30(0.8)d. Since the day was on dry road the coefficent of friction is 0.8. You will then, after multiplying, get (45)²=(√24d)², and you have to square each side to remove the square root symbol, which then becomes 2025=24d, divide both side by 24 giving you the distance, which is 84.38 feet skid mark.