Forces Flashcards
Work Done equation
force x distance moved in direction of force
Moment equation
force x perpendicular distance from pivot
Levers
sun of all clockwise moments about a point = sun of all anti-clockwise moments about a point
What is a Gear?
rotating wheel with teeth that interlocks with another wheel
transmits rotational forces
Pressure equation
force / area = pa
weight equation
mass x gravitational field strength
force equation
spring constant x extension
pressure equation 2
density x height x gravitational field strength
rule about atmospheric pressure
less molecules = fewer collisions = less pressure
speed equation
distance / time
velocity equation
displacement / time
walking, running & cycling velocity’s
walking - 1.5 m/s
Running - 3 m/s
Cycling - 6 m/s
velocity is the _____ on a distance time graph
gradient
what does SUVAT stand for?
S = displacement (m)
U = initial velocity (m/s)
V = final velocity (m/s)
A = acceleration (m/s)
T = time (s)
acceleration equation
change in velocity / time
newton’s first law of motion
a body in motion stays in motion at constant velocity and body at rest stays at rest unless acted upon by a net external force
newton’s second law of motion
a body accelerates when acted upon by a net external force. the acceleration is proportional to the net force and is in the direction which the net force acts
force equation 2
mass x acceleration
newton’s third law of motion
for every action there exists an equal and opposite reaction. if A excerpts a force F on B, the. B excerpts a force of -F on A
what is stopping distance
thinking distance and braking distance
what is braking distance
that distance take. to stop once the brakes are applied
momentum equation
mass x velocity
what is momentum
the property of a moving object. the larger momentum an object has, the harder it is to stop
conservation of momentum
in a closed system, the total momentum before an event is equal to the total momentum after the event
force equation 3
change in momentum / time
what is a scalar quantity?
a physical quantity that only have magnitude (size) e.g. mass and electric charge.
what is a vector quantity?
a physical quantity with both magnitude (size) and direction. e.g. force and weight
what is a contact and non-contact force? give examples
contact force = force that acts between two objects that are physically touching each other e.g. friction, air resistance, tension, reaction force
non-contact force = force acting between two objects that are not touching each other e.g. gravitational force, electrostatic force, magnetic force
what is weight and how do you calculate it?
the force of gravity on a mass
weight = mass x gravitational field strength
what is resultant force and how do you calculate it?
a single force that has the same effect as two or more forces acting together
subtract the magnitude of the smaller force from the larger force
what are some examples of the forces involved in stretching, bending or compressing an object?
stretching = weight of mass and tension in spring
bending = weight and reaction force
compressing = weight and reaction force
why does more than one force need to be applied to an object to change its shape?
a single force would simply cause the object to move in the direction in which the force is applied
what is the difference between elastic deformation and inelastic deformation?
if it returns to its original shape after being stretched its elastic if it doesn’t then its inelastic
what is the extension of an elastic object directly proportional to?
the force applied (provided that the limit of proportionality is not exceeded)
what is the difference between a linear and non-linear relationship between force and extension?
linear = directly proportional
non-linear = not proportional
how do you calculate a spring constant from a linear force-extension graph?
the slope of the graph
what is the equation for elastic potential energy?
= o.5 x spring constant x extension2
how do forces on a system cause a rotation?
the turning effect of the forces causes the object to rotate
what is the difference between distance and displacement?
distance is a scalar meaning only magnitude
displacement is a vector meaning both magnitude and direction
what is terminal velocity?
the steady speed achieved by an object freely falling through a gas or liquid
what is inertia?
an objects resistance to a change in motion
what are the dangers caused by large decelerations?
may cause brakes to overheat and driver to lose control of vehicle
when a force acts on an object that is moving or unable to move what happens?
a change in momentum occurs
