When the car's speed is doubled centripetal acceleration is 8 m/s²
Step-by-step explanation:
We know the equation for centripetal acceleration

where v is the linear velocity and r is the radius.
So we have
a ∝ v²

Given that
a₁ = 2 m/s²
v₁ = 35 mph
v₂ = 70 mph
Substituting

When the car's speed is doubled centripetal acceleration is 8 m/s²