Forces And Motion Flashcards
(26 cards)
In a time graph, what does the gradient of slope represent?
The speed of the object
What does a curved line represent in a time graph?
Acceleration
True of false: force is a vector quantity.
True
What is a vector quantity?
Something with both magnitude and direction.
What effect does force have on an object?
Changes in speed, shape, or direction.
What is the formula for speed?
Distance moved / time taken
What are forces measured in?
Newtons
What is Hooke’s law?
The extension of a spring is directly proportional to the amount of force applied to it.
What is the spring constant?
A measure to see how stiff the spring is, the larger the constant, the stiffer the spring.
What is the limit of proportionality?
It is where hookes law is no longer obeyed
How can you tell where the limit of proportionality is on a graph?
It is where there is no longer a directly proportional relationship, eg. The line starts to curve or go wonky.
What is the elastic limit.
The elastic limit is the point at which the object no longer returns to its original shape once the weights are removed.
What is elastic deformation?
When an object returns to its original length once the forces are removed.
What is inelastic deformation?
When an object remains premantly stretched after removing the forces.
How do you calculate the spring constant of a material?
K = F / e
Spring constant = force / extension
How do you test the elasticity of a material, describe a practical.
- Hand the material with no masses on it and record the original length of the spring.
- Place a known mass on the material and measure the springs new length. Work out the extension by subtracting the original length (no mass) from the new length.
- Repeat step 2 again.
Use your data to calculate the spring constant of each material.
What is the equation for Hooke’s law?
Force = spring constant x extension
F = K x e
When would a moment increase?
If the force is larger, or if the distance to the pivot increases.
How do you calculate the size of a moment?
Moment = force x perpendicular distance from pivot
M = F x d
What is a plastic material?
A material which once the force is removed from the material, it will not return to its original form.
What are the units for moments?
Newton meters (Nm)
True of false: Moments do not have direction
False, moments can be clockwise (CW) or anti clockwise (ACW)
How do you measure the perpendicular distance from a pivot?
It is measure along a line that is at right angles to the direction of the force
What is the principle of moments?
If an object is in equilibrium the total clockwise moment is equal to the total anti-clockwise moment.
Sum of CW moments = sum of ACW moments
