Answer:
The car's skid marks will be 25.4842 m long.
Explanation:
According to Newton's second law:
Force = Mass × acceleration due to car
Also, The formula for frictional force,
Frictional force = μ × Normal Force
Also, Normal force = mass × acceleration due to gravitation(g)
So,
Frictional force = μ × mass × g
The two forces acting horizontally on the tire in opposite directions. So,
Mass × acceleration due to car = μ × mass × g
Solving,
Acceleration due to car = μ × mass × g
Given,
μ = 0.80
Also, 9.81 ms⁻²
So,
Acceleration due to car = 7.848 ms⁻²
Considering the Equation of motion as:
v² = u² - 2.a.s
Brakes are applied ad the car stops. The final velocity of the car (v) = 0 ms⁻¹
Given: Initial velocity of car (u) = 20 ms⁻¹
Acceleration, above calculated = 7.848 ms⁻²
Applying in the equation to calculate the distance as:
(0)² = (20)² - 2×(7.848)×s
So, Distance:
<u>s = 25.4842 m</u>
<u>The skid marks are 25.4842 m long.</u>