IGCSE Physics P1.5 Forces
how to determine the position of the centre of mass of a plane lamina
- hang up the object. - suspend a plumb line from the same place - mark the position of the thread the center of mass is along the line of thread - repeat the above steps with object suspended from different places the center of mass is where these lines cross
Name a form of friction
Air resistance
What is Hooke's law shortened to?
F = kx (k being the spring constant)
Relationship between resultant force, mass, and acceleration
F = ma
What is Hooke's Law written out?
Force = spring constant * (final length of spring - initial length of spring)
How to calculate the resultant force of two or more forces acting on the same line?
Once you find out the magnitude of the force (whether it's positive or negative), you add them.
What can forces change in an object?
Size, shape, and motion
relate pressure to force and area
The equation shows that pressure is directly proportional to force, but inversely proportional to area.
the effect of the position of the centre of mass on the stability of simple objects
The lower the center of gravity of an object is, the stabler it is
What is limit of proportionality/elastic limit.
The maximum extent to which a solid may be stretched without permanent alteration of size or shape. Can be noticed when a line curves upwards on an extension-load graph.
What happens when the resultant force is zero (equilibrium)?
The object stays stationary
What is extension?
When an elastic object, like a spring, is stretched the increased length is called an extension.
What is compression?
When an object decreases in length
what is a plane lamina
a body whose mass is concenctrated in a single plane
What is a spring constant?
a measure of the stiffness of the spring
how to calculate moment
moment (Newton meter) = force (N) x perpendicular distance from the force to the pivot (m)
pressure equations
pressure = force / area
What does a curve up mean on an extension load graph?
so much weight is added to the spring that it becomes damaged. the spring has been stretched beyond its elastic limit.
What does an upwards slanting line mean on an extension load graph?
that, until a certain point, force and extension share a strong positive correlation - the extension of an object is directly proportional to the force acting on it.
What is friction?
the force between two surfaces which impedes motion and results in heating
moment
the turning effect of a force
principle of moments
when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point
equilibrium (moment)
when there is no resultant force and no resultant turning effect
