2. The 2-Mg car has a velocity of V = 100 km/h when the driver sees an obstacle in front of the car. It
takes 0.75 s for him to react and lock the brakes, causing the car to
skid. If the car stops when it has traveled a distance of 170 m, determine the coefficient of kinetic
friction between the tires and the road.
Solution:
𝑣2 = 𝑢2 + 2as
100 km/h = 27.77m/s
According to question car stopped at the end which ; v= 0
0 = 27.772
+ (2)(a) (170)
771.6 =(340)(a)
2.26 m/𝑠2
3. • F= (m)(a )
F= (2000)(2.26)
F= 4520 N
• F= 4520 N
• Friction Force = 4520N
• Friction Force = μ 𝑘 𝑁𝑐
• 𝑁𝑐 = Normal Force = (m)(g)
• 𝑁𝑐 = (2500)(9.81)=19620N
• So
• 4520 = μ 𝑘 19620
• μ 𝑘= 0.23
