# Help with my project

Hi all.I need to prepare a project which measures a physical properties.I selected to measuring length of a material with ardunio.I am new with ardunio can u guys help me ? thx.

If it is about larger objects you can use an SR04 ultrasonic sensor to measure distance easily: http://www.instructables.com/id/Simple-Arduino-and-HC-SR04-Example/

An Arduino is about 2.70 inches long. Just hold it along the material you are measuring, and add up sucessive 2.7 inches.

If you want to do it electronically, first read the post called How to use this forum, then rephrase your question supplying the additional information.

Srijal97:
If it is about larger objects you can use an SR04 ultrasonic sensor to measure distance easily:

How does that help to measure the length of the item? It gives us the distance from our sensor to one face of the object, as long as that face is towards us. But how do we get a reflection off the far side, facing away from us, so we can subtract one from the other and get the length?

ChrisTenone:
An Arduino is about 2.70 inches long. Just hold it along the material you are measuring, and add up sucessive 2.7 inches.

A bit like a Smoot, but smaller.....

JimboZA:
How does that help to measure the length of the item? It gives us the distance from our sensor to one face of the object, as long as that face is towards us. But how do we get a reflection off the far side, facing away from us, so we can subtract one from the other and get the length?

You just need a reference plane, somekind of surface(like a cardboard) placed accordingly to reflect the ultrasound waves.

Srijal97:
You just need a reference plane, somekind of surface(like a cardboard) placed accordingly to reflect the ultrasound waves.

Yeah well while you're arseing around doing that, measure it with a ruler.

But that said, it might be that the object is conveniently placed next to such a plane, like parked against a wall. We won't know until the OP gives more detail.

JimboZA:
Yeah well while you're arseing around doing that, measure it with a ruler.

But that said, it might be that the object is conveniently placed next to such a plane, like parked against a wall. We won't know until the OP gives more detail.

Yea right.
For tall objects you could also use two lasers at a known angle, measure base using sr04 and find height using trignometry. If this is a school project it should be sufficiently cool.