Three methods by which the value of the unknown resistance can be determined​

Explanation:

Given data;

time = 0.5 sec; velocity, v= 70 m/hr= 102.667 ft/sec; skid distance = 80 ft, efficiency = 100 %

Step 1: calculate distance traveled, dt =velocity * time = 102.667 * 0.5 = 51.33 ft

Step 2: Calculate distance traveled before applying brake = distance traveled + skid distance = 51.33 ft + 80 = 131.33 ft

Thus, required distance = 250-131.33 = 118.67 ft

Step 3: Calculate velocity,using this formula;

V = √[Required distance * reaction time(coefficient of resistance + percentage grade)]

V = √[118.67 * 30(0.013 +0.02)]

V =√118.67 * 0.99

V= √117.4833

V = 10.8 ft/sec