Forces & Elasticity (OCR GCSE Physics A (Gateway)): Flashcards
Exam code: J249
1/410Still learning
Know0
- FrontChanging Shape
Define deformation.
Was this flashcard helpful?
Cards in this collection (41)
Define deformation.
Deformation is a change in the shape of an object caused by a force.
True or False?
Only one force is needed to change the shape of a stationary object.
False.
At least two forces must act on a stationary object to change its shape. A single force would cause the object to accelerate instead.
why do two forces need to act for a stationary object to change shape?
A single force would cause the object to accelerate rather than deform. Two forces acting in opposite directions keep the object stationary while changing its shape.
An object can change shape by stretching, .......... or compressing when forces are applied to it.
An object can change shape by stretching, bending or compressing when forces are applied to it.
Define elastic deformation.
Elastic deformation occurs when an object returns to its original shape and size after the stretching force is removed.
True or False?
A rubber band that returns to its original length after stretching has undergone plastic deformation.
False.
This describes elastic deformation. Plastic deformation is when an object does not return to its original shape after the force is removed.
how does plastic deformation differ from elastic deformation?
In plastic deformation, the object remains permanently stretched and does not return to its original shape when the force is removed. In elastic deformation, it does return to its original shape.
Define plastic deformation.
Plastic deformation occurs when an object remains permanently stretched and does not return to its original shape after the force is removed.
Complete the table to show whether each material typically undergoes elastic or plastic deformation.
Material
Type of deformation
Steel spring
Clay
Rubber band
Plastic
Complete the table to show whether each material typically undergoes elastic or plastic deformation.
Material
Type of deformation
Steel spring
Elastic
Clay
Plastic
Rubber band
Elastic
Plastic
Plastic
State Hooke's Law.
Hooke's Law states that the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality.
True or False?
If the force applied to a spring doubles, its extension also doubles, provided the limit of proportionality has not been exceeded.
True.
Hooke's Law states that extension is directly proportional to force. Doubling the force therefore doubles the extension, as long as the limit of proportionality is not exceeded.
The Hooke's Law equation is F = k × x, where F is force in newtons, k is the .......... and x is the .......... in metres.
The Hooke's Law equation is F = k × x, where F is force in newtons, k is the spring constant and x is the extension in metres.
What does the spring constant tell you about a spring?
The spring constant is a measure of the stiffness of a spring. A higher spring constant means the spring is stiffer and requires more force to produce the same extension.
Define limit of proportionality.
The limit of proportionality is the point beyond which the extension of a spring is no longer directly proportional to the applied force.
True or False?
The unit of the spring constant is N/m.
True.
The spring constant k is measured in newtons per metre (N/m), since it represents the force needed per unit of extension.
How is the extension of a spring calculated from its lengths?
Extension = final length − original length. The original length is measured before any force is applied, and the final length is measured after the spring has stretched.
Complete the table to show how force and extension are related when Hooke's Law applies.
Force applied
Extension
Doubled
Halved
Tripled
Complete the table to show how force and extension are related when Hooke's Law applies.
Force applied
Extension
Doubled
Doubled
Halved
Halved
Tripled
Tripled
What is a linear relationship (force-extension)?
A linear relationship between force and extension produces a straight line on a force-extension graph, showing that force and extension are directly proportional.
True or False?
A curve on a force-extension graph shows that the material obeys Hooke's Law.
False.
A curve on a force-extension graph shows a non-linear relationship, meaning force and extension are no longer directly proportional and the material does not obey Hooke's Law.
What does the gradient of the linear part of a force-extension graph represent?
The gradient of the linear region equals the spring constant k. A steeper gradient means a larger spring constant and a stiffer spring.
On a force-extension graph, the linear region shows that force and extension are .......... proportional. Beyond the limit of proportionality, the graph becomes ..........
On a force-extension graph, the linear region shows that force and extension are directly proportional. Beyond the limit of proportionality, the graph becomes curved.
Define spring constant (from a graph).
The spring constant is the gradient of the straight-line region of a force-extension graph. It has units of N/m and indicates how stiff the spring is.
True or False?
The spring constant can only be determined from the non-linear part of a force-extension graph.
False.
The spring constant is found from the gradient of the linear (straight-line) region, not the non-linear (curved) part.
How can you tell from a force-extension graph that a material has exceeded its limit of proportionality?
The graph changes from a straight line to a curve. Once the line curves, the extension is no longer directly proportional to the force and the material no longer obeys Hooke's Law.
What is a non-linear relationship (force-extension)?
A non-linear relationship between force and extension is shown by a curve on a force-extension graph. It means force and extension are no longer directly proportional.
Define elastic potential energy.
Elastic potential energy is the energy stored in an elastic object when work is done on it, such as when a spring is stretched or compressed.
True or False?
When a spring is stretched within its limit of proportionality, the work done on it equals the elastic potential energy stored.
True.
Provided the spring has not exceeded its limit of proportionality, all the work done on the spring is transferred to its elastic potential energy store.
The elastic potential energy stored in a spring is calculated using Ee = ½ × k × e2, where k is the .......... and e is the .......... in metres.
The elastic potential energy stored in a spring is calculated using Ee = ½ × k × e2, where k is the spring constant and e is the extension in metres.
why does doubling the extension of a spring quadruple the elastic potential energy stored?
The elastic potential energy equation includes e squared. Doubling e gives (2e)2 = 4e2, so the energy stored is quadrupled. The relationship between energy and extension is not linear.
Define work done on a spring.
Work done on a spring is the transfer of energy to its elastic potential energy store when it is stretched or compressed by a force.
True or False?
The equation Ee = ½ × k × e2 can be used for a spring stretched beyond its limit of proportionality.
False.
The equation Ee = ½ × k × e2 only applies when the spring has not been stretched beyond its limit of proportionality. Beyond this point, Hooke's Law no longer holds.
what energy transfer occurs when a spring is compressed or stretched by a force?
Work done by the force is transferred to the spring's elastic potential energy store. The amount of energy stored depends on the spring constant and the extension (or compression).
Complete the table showing the variables in the elastic potential energy equation Ee = ½ × k × e2.
Symbol
Quantity
Unit
Ee
k
e
Complete the table showing the variables in the elastic potential energy equation Ee = ½ × k × e2.
Symbol
Quantity
Unit
Ee
Elastic potential energy
J
k
Spring constant
N/m
e
Extension
m
What is the independent variable (force & extension PAG)?
The independent variable in the force-extension investigation is the force applied to the spring, controlled by adding known masses.
True or False?
In the force-extension PAG, measurements should be taken at eye level to reduce parallax error.
True.
Reading the ruler at eye level reduces parallax error, a systematic error that would shift all readings in the same direction and affect the accuracy of the results.
How is the force applied to the spring calculated in the force-extension PAG?
The force equals the weight of the masses added. Weight is calculated using W = m × g, where m is the mass in kg and g = 10 N/kg. Each mass is multiplied by g to find the force in newtons.
In the force-extension PAG, the extension is found by subtracting the .......... length from the final length of the spring.
In the force-extension PAG, the extension is found by subtracting the original length from the final length of the spring.
What is a fiducial marker (spring experiment)?
A fiducial marker is a pointer attached to the spring to allow more precise and consistent measurement of the spring's extension, reducing random errors.
True or False?
Readings should be taken immediately after adding each mass to get the most accurate extension measurement.
False.
You should wait a few seconds after adding each mass to allow the spring to fully extend before recording the reading. Taking readings too quickly introduces error.
why should results be repeated and an average taken in the force-extension PAG?
Repeating measurements and averaging reduces the effect of random errors, making the results more reliable. It also helps identify any anomalous readings that should be excluded.
Complete the table to show the variables in the force-extension PAG.
Variable type
Variable
Independent
Dependent
Control
Complete the table to show the variables in the force-extension PAG.
Variable type
Variable
Independent
Force (F)
Dependent
Extension (x)
Control
Spring constant (k)
Sign up to unlock flashcards
or