 # How To Measure Car Speed? Everything You Need To Know Do you know how to measure car speed? It’s not as difficult as you might think! There are three main ways to do it: using a speedometer, a radar gun, or a GPS. In this blog post, we will discuss each of these methods and explain how they work. We will also provide some tips on how to use them effectively. So, whether you are a law enforcement officer who needs to accurately measure car speeds or just someone who wants to know how fast your car can go, read on for all the information you need! ## Speedometer

Speedometer is the most common method of measuring car speed. It is a device that is fitted to the car and measures the speed at which the car is travelling. The speedometer will usually have a needle that points to the current speed on a dial.

A radar gun is a handheld device that uses radio waves to measure the speed of a moving object. Radar guns are commonly used by law enforcement officers to measure the speeds of cars on the road. They can also be used by anyone who wants to know how fast their car is going.

If you’ve read our article about motion, you’ll know that speed is very simply defined: it’s the distance you travel divided by the time you take. So if you go 200 kilometers and it takes you four hours to do it, your average speed is 50 kilometers per hour.

## GPS

GPS stands for global positioning system. GPS devices use satellite signals to determine their location and can also be used to track the movement of objects, including cars. GPS devices can be used to measure the speed of a car by tracking its movement over time.

All of these method uses a common formula to measure distant which is V=S/T. The complex mechanism of car speedometers, radar guns and GPS system is based on this simple formula.

The Speedometer, Radar Gun And GPS returns the values which by putting into the distance time graph derived formula yields speed. When we get information of distance and time we can calculate speed easily.

## FAQs

#### What Is Acceleration

Acceleration is rate of change of velocity so if velocity is changing we will have acceleration if car is moving with constant (unchanged) velocity we will not have acceleration.

#### Explain how a car moving at constant speed has a nonzero average acceleration

If car is moving with constant speed then it's not changing its velocity and acceleration is measured by changing velocity so in normal condition the acceleration will be zero. However, if a car is moving in circle or changing its direction then it can have a non zero average acceleration.

#### What is the acceleration of a car that travels in a straight line at a constant speed?

Acceleration will be zero if the car is moving in a straight line with constant velocity. However, if the car is changing its direction then it will have acceleration.

#### A car traveling with constant speed travels 150 km in 7200 s. what is the speed of the car?

It will be 20.8333m/s = V or 46.60276485 miles/hour of a car traveling with constant speed travels 150 Km in 7200 s. Lets dive into the question to find the solution.

Lets say the distance in the question is 150km breaking so distance S=150Km

In the given problem the time is 7200s so T=7200s

The speed of the car is constant so we can use S=VT where S is distance, V is speed and T is time.

From the equation we have one unknown so by putting the values

150Km = V (7200)s

Factoring 7200s out we will get

150Km/7200s = V

0.02083333 Km/s = V

If we want the speed in m/s then

0.0208333 x 1000 m/s = V

20.8333m/s = V

If you want the answer in miles per hour then multiply the answer with 2.23694 because 1m/s = 2.23694 m/h.

46.60276485 miles/hour = V

Lets take another example

#### A car travels 100 meters in 5 seconds. what is the speed of the car?

It will be 20m/s if a car travels 100 meters in 5 seconds. From the distance time graph we know to calculate speed we can divide distance with time provided that the speed is constant so we get 20m/s.

From the question it is given that Distance S = 100m and Time T = 5s

From the distance time graph we know S=VT

We have 3 variables 2 known values and 1 unknown so by putting the values

100m = V 5s

100m/5s = V

20m/s = V

#### A car is driving at a speed of 60 mi/h. what is the speed of the car in feet per minute?

Speed will be 2640 Feet/Minutes if a car is driving at a speed of 60 miles per hour.

There are 5280 feet in 1 miles and there are 60 miles in 1 hour so in the given question, V=30mi/h

V = 30 (5280) Feet / 1 x (60) minutes

V= 158400/60

V = 2640 Feet/Minutes

#### When the speed of your car is doubled, by what factor does its kinetic energy increase?

If we take the mass as constant then we can say that the new K.E will be 4 times the previous K.E if we double the car speed.

Let's see the formula to know what will happen so the formula of Kinetic Energy is

K.E = 1/2 mv^2

In the question we have given that speed is doubled so we can make the speed in the equation twice so

K.E = 1/2 m(2v')^2

K.E = 1/2 m 4v^2

Lets factor the 4 out and we'll get

(K.E)' = 4(1/2mv^2)

So
The new K.E will be 4 times the previous K.E

(K.E)' = 4 (K.E)

#### What is the kinetic energy of a 2100 kg car traveling at a speed of 30 m/s (≈65 mph)?

Kinetic energy of a 2100kg car traveling at a speed of 30m/s will be 945000 J.

K.E = 1/2 mv^2

K.E = 0.5 x (2100kg) x (30m/s)^2

K.E = 1050Kg x 900 (m/s)^2

K.E = 945000Kgm^2s^-2

As 1 J = Kg m^2 s^-2

K.E = 945000 J

#### What is the speed of a car that travels a distance of 520 kilometers in 12 hours?

Speed of a car will be 43.3333333333 km/h or 12.037037m/s if it travels a distance of 520 km in 12 hours assuming the speed was constant.

From the speed time graph we know that S = VT so by putting the values in equation we get

520km = V 12h

Dividing 12h On Both Sides

520km/12h = V 12h/12h

520Km/ 12h = V(1)

43.3333333333 km/h = V ........(1)

we know that 1 km = 1000meters and 1 hours = 60 minute and every minutes has 60 seconds so 1 hour = 60 x 60 s

1 Hour = 3600s

If we put the values in the equation 1 we'll get

(43.333333333 x 1000 )/ 3600s = V

12.037037m/s = V

#### The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is?

The time it takes a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2 is 15 seconds.

If the car is at rest we can make initial velocity to 0 so Vi = 0 after accelerating the speed becomes 30 m/s. In the question acceleration is given which is 2 m/(s^2) so we can use distance time graph formula to find time.

Vf= Vi +a(t)

By putting values

30 = 0 + 2 m/s2(t)

30 = 2 t

30/2 = t

15s = t

So it will take 15 seconds for a car to attain a speed of 30 m/s when accelerating from rest at 2 m/s2.

#### What constant acceleration, in si units, must a car have to go from zero to 60 mph in 10 s ?

A car has constant acceleration of 2.6822333 m/(s)^2 to go from 0 to 60mph in 10s.

First the car is at rest so Vi=0m/s.

After 10 seconds the speed becomes 60 mph so, T = 10s and Vf = 60mph.

By distance time graph we know Vf = Vi + a (t)

now we have only one variable so we can calculate this equation.

First lets convert the speed which is in mpg into m/s (S.I units).

As 1 mile = 1609.34 meters and 1 Hour = 60 minutes.

Vf = (60 x 1609.34) / 60 minutes

as there are 60 seconds in minutes so

Vf = (60 x 1609.34) meters / 60 x 60 second

Vf = 26.8223333333 m/s

Now lets calculate acceleration

Vf = Vi + a (t)

26.8223333 m/s= 0 + a (10s)

26.8223333 m/s= a (10s)

Dividing 10s on Both Sides

26.8223333 / 10 = a

2.6822333 m/(s)^2 = a

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