Answer:
52.24 km
Step-by-step explanation:
Given that,
The distance needed to stop a car, d, varies directly as the square of the speed, s, at which it is travelling.
d = ks²
Where
k is constant
When s₁ = 70 km/hr, d₁ = 40 m, s₂ = 80 km/hr, d₂ = ?
So,
[tex]\dfrac{d_1}{d_2}=\dfrac{s_1^2}{s_2^2}\\\\d_2=\dfrac{d_1s_2^2}{s_1^2}\\\\d_2=\dfrac{40\times 80^2}{70^2}\\\\d_2=52.24\ km[/tex]
So, the new distance is 52.24 km.
