# Science>physics A car tavels at 20 km/h for 1 hour, at 30km/h for 2 hours, and at 40 km/h for another 2 hours. calculate the average speed of car.

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Hi,

The average speed of car would be : 32 kmph

Good Luck.

Live, Love Laugh.

Posted on Sep 11, 2008

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Posted on Jan 02, 2017

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## Related Questions:

### If 360 km per hour is equal to 40 miles per hour, please show me how to calculate using formular

360 km/hr is NOT 40 miles/hr.
1 mile is about 1.6 km
To go from km to miles, multiply by 0.62
To go from miles to km, multiply by 1.6

Kilometers per hour to Miles per hour

Feb 23, 2017 | Cars & Trucks

### If a car went from 0 to 100 km/h in 3.7 seconds, using the accelerationn formula how would I find the average acceleration?

Convert the speed from km / h to m/s.
Change in speed = (Final speed (in m/s) - initial speed (0))/ 3.7 s
The result is the average acceleration in m / s^2.
100 km /h = (100 000 m)/ (3600 s)= 27.7778 m/s

May 27, 2014 | Texas Instruments TI-30 XIIS Calculator

### What's the average ball speed?

The average ball speed for a bowling is about 10 miles per hour to15 miles per hour with professional bowlers averaging about 20 to 25 miles perhour, the power of the throw depends on the bowling game type you're playingand your physical strength. You can improve your throwing speed by practicingyour throws and strengthening you forearm.

Jul 23, 2012 | Sport & Outdoor - Others

### Meter to kilometer

There are 1000 meters in a kilometer and 3600 seconds in an hour (60 seconds per minute, 60 minutes per hour).

Press 8 0 0 / 5 0 * 3 6 0 0 / 1 0 0 0 =
or 8 0 0 / 1 0 0 0 * 3 6 0 0 / 5 0 =

The result should be 57.6 kph.

Nov 11, 2011 | Casio FX-115ES Scientific Calculator

### On a round trip of 400km,a pilot wants to determine the airspeed of hiis light plane. He flies the entire distance at the same airspeed for the first 200km a steady headwind slows him down by 30km/hour....

v will represent plane's airspeed.

We can divide pilot's trip in 2 parts:
1. first 200km, when he is flying with speed v. The time it takes him to fly this part of trip is t=200/v
2. last 200km, when he is flying with speed v-30. The time it takes him to fly this part is 200/(v-30)
The time it takes him for second part of trip is also equal to 1.5-t (because entire trip takes 1.5h), so now we can write equation:

1.5-t=200/(v-30)

We also know that t=200/v so we substitute that into equation:

1.5-200/v=200/(v-30)

To solve this equation we multiply it with v*(v-30)=v^2-30v first. We get:

1.5(v^2-30v)-200(v-30)=200v

Now we get rid of brackets:

1.5v^2-45v-200v+600-200v=0

or

1.5v^2-445v+600=0

This is quadratic equation, so we get 2 solutions (sqrt= square root):

1. v=(445+sqrt(445^2-4*1.5*600))/(2*1.5)=295.3 km/h
2. v=(445-sqrt(445^2-4*1.5*600))/(2*1.5)=1.4 km/h
We know that only v=295 km/h is solution because if 1.4 km/h was solution that would mean that second part of trip plane was flying with speed 1.4-30= -28.6 km/h, so that would mean he was flying backwards (which we know he didn't because it's round trip). Speed 1.4 km/h is also not physical solution, because plane wouldn't be able to take off with such small speed :)

Sep 08, 2011 | Casio ClassPad 300 Calculator

### What is the speed of an automobile in kilometers per hour if it is trveling 45 miles per hour?

Hi,

There are 1.609344 kilometers in 1 mile. So you can just put it this way.

45 miles x 1.609344 kilometers
1 mile

The answer is 72.42048 km or just 72.42 kilometers

Therefore the automobile is traveling 72.42 kilometers per hour.

Hope this helps.

Jun 27, 2011 | Casio FX-9860G Graphic Calculator

### A bicycle travels 12 km in 40 min. What is its average speed in km/hr?

18 km/hour

The bike is traveling at the speed of 12/40 = 6/20 =18/60

18 km/60 minutes

Jun 21, 2011 | Computers & Internet

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