Challenge: In a 60 km/h speed zone the police set up a digitector, placing 2 cables across the road, 5m apart The time taken for cars to cross both cables was recorded. One car took 0.2 seconds to cross the cables. Was it speeding? If so by how much?

The answer to your question is given below.

Explanation:

The following data were obtained from the question:

Speed limit = 60 km/h

To know if the car was speeding, let us calculate the speed of the car.

This can be obtained as follow:

Distance (d) = 5 m

Convert 5 m to km

Recall:

1000 m = 1 km

5 m = 5/1000

5 m = 0.005 km

Time (t) = 0.2 sec.

Convert 0.2 sec to hour.

Recall:

3600 secs = 1 h

Therefore,

0.2 sec = 0.2/3600

0.2 sec = 5.56×10¯⁵ h

Thus,

Distance (d) = 0.005 km

Time (t) = 5.56×10¯⁵ h

Speed of car =?

Speed = Distance /time

Speed = 0.005/5.56×10¯⁵

Speed of the car = 90 km/h

Comparing the speed of the car (i.e 90 km/h) to the speed limit of the zone (i.e 60 km/h), we can see that the car is on a high speed since its speed (i.e 90 km/h) is higher than the speed limit of the zone (i.e 60 km/h).

Speed of the car = 90 km/h

Speed limit = 60 km/h

Difference = 90 – 60

Difference = 30 km/h

Therefore, the car is speeding by 30 km/h more compared to the speed limit.