Final answer:
Downshifting before a curve is important when the road is wet, icy, or when the curve is especially sharp to maintain vehicle control. Banked curves on race tracks allow higher speeds, but on public roads safety and control take precedence, and downshifting helps manage speed and traction.
Step-by-step explanation:
There are special conditions where you should downshift before entering a curve to maintain control of the vehicle through the application of engine braking, which can provide better stability especially under less than ideal road conditions. These conditions include:
- When the road is wet, as the reduced traction would require slower speeds to navigate a turn safely.
- When the road is icy, since ice can significantly reduce friction and increase the likelihood of sliding.
- When the curve is sharp, downshifting helps lower your speed and provides more control, helping to ensure that the vehicle stays on the intended path.
- When the curve is gentle, it may not be as necessary to downshift, but it's still a good practice if the vehicle's speed is too high.
Banked curves, like those found on race tracks, allow vehicles to negotiate turns at higher speeds due to the incline providing a component of centripetal force. However, in everyday driving situations on public roads, especially under adverse weather conditions, downshifting before a turn can provide extra control. When entering a banked curve at a non-ideal speed, or on a curve without banking, the reliance on tire road friction is greater.
In the context of a race track curve, drivers may use the inside path or 'cutting the corner' to achieve higher speeds during the turn, as the shorter path allows for a more efficient turn. However, on public roads, this principle is not typically applied, and safety takes priority over efficiency or speed, which is why downshifting is important for safe vehicle handling.