Question

passage 1
students used 2 methods to calculate d, a cars total stopping distance; d is the distance a car travels from the time a driver first reacts to an emergency until the car comes to a complete stop.
in method 1, r is the distance a car travels during a drivers assumed reaction time of 0.75 sec, and b is the average distance traveled once the brakes are applied. method 2 assumes that d = initial speed in ft/sec × 2 sec. table 1 lists r, b, and d for various initial speeds, where d was computed using both methods. figure 1 contains graphs of d versus initial speed for method 1 and method 2.

a driver was traveling 60 mi/hr when she spotted an accident and immediately applied her brakes. it took her 2 sec from the time she spotted the accident until she brought her car to a complete stop. according to method 2, how far did her car travel during the 2 sec interval?
○ f. 58 ft
○ g. 118 ft
○ h. 176 ft
○ j. 234 ft

Explanation:

Step1: Identify initial speed and Method 2

The driver's initial speed is 60 mi/hr. From Table 1, for Method 2, when initial speed is 60 mi/hr, the D (total stopping distance) is 176 ft. Wait, but let's check the problem again. Wait, the problem says "how far did her car travel during the 2 sec interval" according to Method 2. Wait, maybe I misread. Wait, Method 2: D = initial speed in ft/sec × 2 sec? Wait, no, the passage says: "In Method 2, it is assumed that \( D=\text{initial speed in ft/sec} \times 2 \) sec. Tables are applied. Method 2 assumes that \( D=\text{initial speed in ft/sec} \times 2 \) sec." Wait, first, convert 60 mi/hr to ft/sec.

1 mile = 5280 feet, 1 hour = 3600 seconds. So \( 60 \, \text{mi/hr} = 60 \times \frac{5280}{3600} \, \text{ft/sec} = 88 \, \text{ft/sec} \). Then Method 2: \( D = 88 \times 2 = 176 \, \text{ft} \). Alternatively, from Table 1, when initial speed is 60 mi/hr (or 88 ft/sec, since 60 mi/hr is 88 ft/sec as per Table 1: initial speed (mi/hr) 60, initial speed (ft/sec) 88), and Method 2's D is 176 ft. So that matches.

Step2: Confirm from Table 1

Looking at Table 1, for initial speed 60 mi/hr (row where initial speed (mi/hr) is 60), Method 2's D is 176 ft. So the distance traveled during 2 sec interval (Method 2) is 176 ft.

Answer:

H. 176 ft