Physics || Elasticity Flashcards
An Object Can Only Stretch, Compress Or Bend When?
There is more then one force acting on the object,
Otherwise, the object would just move in the direction of the force, instead of changing shape.
Elastically Distorted Means?
It can go back to its original shape and length after the force has been removed.
Elastic Objects Are?
Objects that can be elastically elastically distorted.
Elastic Limit?
Point where an object stops distorting elastically and begins to distort inelastically.
When A Force Stretches Or Compressed An Object, What Happens?
Causes energy to be transferred to the elastic potential energy store of the object,
If it is elastically distorted, ALL this energy is transferred to the elastic potential energy store.
Extension Is Directly Proportional To?
Force,
This means that there is a linear relationship between force and extension.
Force-Extension Graph?
Would be a straight line because they are directly proportional.
Formula For Force?
Force (Newton’s)
= Extension (In Metres) x Spring Constant (N/M).
Spring Constant Depends On?
Material that you are stretching,
A stiffer spring has a greater spring constant.
The Formula Also Works When Trying To Work Out?
Compression,
Just replace extension with the difference between the natural and compression lengths.
Why Does Force Against Extension Graph Start To Curve?
There is a maximum force,
The curve shows that extension is no longer proportional to force,
Relationship is now non-linear,
This is known as the limit of proportionality.
Elastic Limit?
The point marked on the graph where the object is permanently stretched.
Practical - Set Up?
Set up an apparatus with a weighted stand (big long things on a stand we use),
A fixed ruler along the stand,
A clamp on the top of the stand,
A spring hanging off the clamp,
Put a mass (100g weights) on the stand,
Make sure to have lots of extra masses.
Practical - Investigating The Link Between Force And Extension?
Measure the natural length of the spring,
Add a mass to the spring and allow the spring to come to rest,
Record the mass you put on and measure the new length (the difference in length is the extension),
Repeat this process until you have enough measurements (no less than 6),
Plot a force-extension graph of your results.
Practical - How To Make It Accurate?
Add thin strips of tape to the top and bottom of the spring to make sure the reading from the ruler is accurate,
Make sure ruler is fixed straight on the weighted stand,
Take reading at eye level.
The Extension Is?
The difference from the normal to the new length.
Practical - Results Show?
The larger force will cause a larger extension,
This means more work needs to be done to cause a larger extension,
The force doing work is gravity (gravitational force) and for elastic distortions, this Force is equal to F= KX.
How To Find Work Done On Force-Extension Graph?
You can find work done by calculating the area under the linear section,
Just the linear section, not the non-linear part of the graph,
Make sure to work out the area like it was a triangle, so times the two numbers and divide by two.
Work Done Is Equal To ……?
Work done to the spring is always equal to the energy stores in its elastic potential energy store,
This is only true when the spring has not stretched past it’s elastic limit,
You would use the equation E = 1/2 x K x X2 To Find the energy in the potential energy store.
Formula For Energy Transferred In Stretching?
E = 1/2 x K x X2,
k - Spring constant measured in N/M,
X - Extension measured in metres (this must be squared).
