In the traffic of cities and highways, we come across signs that guide us on the velocity maximum allowed for traffic. Failure to comply with these laws can generate fines and legal penalties allowed by the Brazilian Traffic Code. But how is it possible to know the speed of a car if, located outside the vehicle, we cannot observe its speedometer?
The average speed of a vehicle is calculated from the space traveled It's from time taken to traverse such space. By dividing space by time, we get the average speed of the vehicle.
How do radars work?
There is a system (fixed or mobile radar) that calculates the average speed of the vehicle in certain stretches. It works like this: two markings – A and B – are made in a very short stretch. The system marks the time it takes the vehicle to go from A to B. dividing the distance from A to B by the time it took the mobile to travel through that space, we get the average speed of the vehicle on the way.
Average speed equals distance traveled divided by course time
Formula for calculating average speed
The expression that calculates the average speed of a mobile is:
Examples:
1º) Let's assume that a 50 km stretch of highway is monitored by the Highway Police. The maximum speed allowed on the stretch is 80 km/h. A driver covered the 50 km stretch in 30 minutes. Calculate if he exceeded the allowed speed limit.
Resolution:
30 minutes corresponds to 0.5 hours.
Vm = 50
0,5
Vm = 100 km/h
This driver walked above the maximum speed allowed on the stretch monitored by the Highway Police.
2º) In a Formula 1 race, the 1st place finisher completed 60 laps on a 4 km long circuit in 1 hour and 12 minutes. Calculate the average speed developed by the car disregarding the stops for filling and changing tires.
1 hour and 12 minutes correspond to 1.2 hours.
60 x 4 = 240 km
Vm = 240
1,2
Vm = 200 km/h
The average speed developed by the car in the race was 200 km/h.
by Mark Noah
Graduated in Mathematics
Source: Brazil School - https://brasilescola.uol.com.br/matematica/equacoes-no-calculo-velocidade-media-um-veiculo.htm
