AS Mechanics Flashcards
gravity
force of attraction between all objects
inextensible string
a string that does not stretch under load- acceleration is the same in objects connected by a inextensible string
light object
mass of the object is small compared to other masses, like a string or pulley (treat objects as having zero mass)
smooth surface
assume there is no friction between the surface and any object on it
weight
gravitational force that acts vertically downwards
friction
a force that opposes the motion between two rough surface
normal reaction
the force which acts perpendicular to a surface when an object is in contact with the surface
tension
the force acting on an object when it is being pulled along by a string
air resistance
opposes motion
buoyancy
the upward force on a body that allows it to float or rise
vector
a quantity with both magnitude and direction (positive or negative)
scalar
a quantity with magnitude only (only positive)
velocity
rate of change of displacement
Displacement-time graphs
Gradient represents the velocity
Average velocity= displacement from starting point/ time taken
Average speed= total distance travelled/ time taken
acceleration
rate of change of velocity
Velocity-time graphs
Gradient represents the acceleration
Area under graph represents the distance travelled
SUVAT Equations
v= u + at s= 1/2 (u + v)t v^2= u^2 + 2as s= ut + 1/2 at^2 s= vt - 1/2 at^2
Force of gravity
It causes all objects to accelerate towards the earth. If you ignore the effects of air resistance, the acceleration is constant. The acceleration does not depend on the mass of the object
Acceleration due to gravity
Modelled as g= 9.8 m/s^2
Newton’s first law of motion
an object at rest and an object moving with constant velocity will continue in the same state unless acted upon by an unbalanced force
resultant force
causes the object to accelerate in the same direction as the resultant force
Newton’s second law of motion
the force needed to accelerate a particle is equal to the product of the mass of the particle and the acceleration produced (F=ma)
Connected particles
When all parts of the system are moving in the same straight line, the whole system can be treated as a single particle
Newton’s third law of motion
for every action there is an equal and opposite reaction
