Mathematics for IGCSE & O level - Proportion (Section 1 - No. 16)
The braking distance, *d*, of a car is directly proportional to the square of its speed, *s*. If the braking distance is 6 meters when the speed is 10 m/s, what is the braking distance when the speed is increased by 200%?
12 m
18 m
24 m
54 m
설명
d = ks^2. So, 6 = k(10)^2; k = 6/100. If speed increases by 200%, then new speed is 3*10 = 30 m/s. d = (6/100) * (30)^2 = 54.