A learner driver practises controlled stops in a closed training area. A signal lamp changes colour and the driver applies the brakes as soon as possible.
The same car and driver are used for both tests. The speed and the driver's reaction time are unchanged.
| quantity | value |
|---|---|
| speed of the car | 14 m/s |
| driver's reaction time | 0.60 s |
| braking distance on the dry surface | 19.0 m |
| stopping distance on the wet surface | 36.4 m |
State the name of the distance travelled between the signal changing colour and the brakes beginning to act.
Calculate the distance travelled during the driver's reaction time.
Use the equation
d=v×td=v\times td=v×t
Calculate the stopping distance of the car on the dry surface.
Calculate the increase in stopping distance on the wet surface compared with the dry surface.
Suggest one reason for this increase.