Force and Motion Flashcards
- a push or a pull
- an agent that alter the velocity of a body by changing its speed or direction
force
basic forces in nature
- gravitational force
- electromagnetic force
- strong nuclear force
- weak nuclear force
force of attraction that acts over a large distance
gravitational force
electric and magnetic interaction fused into a single interaction
electromagnetic force
exist between nuclear particles ; the nuclear binding force; a short ranged force
strong nuclear force
responsible for the very slow nuclear decay processes (radioactivity) like beta decay of the neutron
weak nuclear force
classification of forces
- effects on motion (efforts)
- line of action
- relation to work
- interaction of bodies
produce no motion or motion with constant velocity
balanced forces
produce accelerated motion
unbalanced forces
may go in the same direction or in opposite direction
parallel forces
those that met at a point
concurrent forces
can do work and can be stored as energy
conservative forces
can do work but cannot be stored
non-conservative forces
when an object is pushed by another, the two bodies are in contact with each other
contact force
- force may act at a distance
- there is no contact between the body exerting the force and the body being acted upon
distant force
continuous change in position with reference to a fixed point
motion
branch of physics concerned with the study of motion and what produces and affect it
mechanics
deals with the description of motion of objects without consideration of what causes the motion (quantitative)
kinematics
analysis of the causes of motion
dynamics
2 important aspects of motion
- a change of position or displacement
- the passage of time
- a measurement of how fast one is moving
- defined as distance per unit time
speed
speed accompanied with direction
velocity
rate at which the motion was changed
acceleration
a body that is not in uniform motion is said to be _____
accelerating
a state of fall under the influence of only gravity- free from air resistance
free-fall
average value of free-fall’s acceleration
9.8 m/s squared
3 conditions wherein acceleration occurs
- change in the magnitude of the object’s velocity, or change in speed
- change in direction of the object’s velocity
- both change in speed and velocity
Newton’s Laws of Motion
- law of inertia
- law of acceleration
- law of interaction
measure of the inertia of an object
mass
force of gravity on the object
weight
the change in the state of motion of objects is caused by a _____
net force
resistance of an object to changing its state of rest or state in motion/to continue moving at uniform velocity
inertia
“Any object will continue in its state of rest or uniform velocity unless acted on by a net force”
law of inertia
“When acted on by a net force, an object will accelerate proportional to the amount of the net force”
law of acceleration
SI unit of acceleration
Newton
proportional to the net force and inversely proportional to the mass of the object
acceleration
“To every action there is an equal and opposite reaction”
law of interaction
“Every particle in the universe attracts every other particle in the universe with a force that is proportional to the product of the two particles’ masses and inversely proportional to the square of the distance between them”
law of universal gravitation
state of balance
equilibrium
- bodies which are at rest
- no motion is produced
static equilibrium
body that moves with uniform motion
dynamic equilibrium
states of equilibrium
- stable
- unstable
- neutral
stability of an object is affected by the:
- position of the center of gravity (lower)
- area of the base (larger)
- weight of the object (greater)
conditions for equilibrium
- translational / force equilibrium
- rotational / torque equilibrium
“At equilibrium, the forces are such to cancel one another out” or “The sum of all the forces is equal to zero”
translational / force condition
“The sum of the torques acting on an object, as calculated about any axis, must be zero”
rotational / torque condition
a torque that tends to rotate the object counterclockwise is usually considered _____
positive
a torque that tends to rotate the object clockwise is usually considered ____
negative
- force that opposes motion
- parallel to the surface which are in contact
friction
types of friction
- static friction
- kinetic friction
friction between two surfaces that are not sliding relative to each other
static friction
friction between surfaces that are sliding over one another
sliding friction
friction between two surfaces when one surface is rolling over another
rolling friction
ratio of the friction force to the normal force passing the two surfaces together
coefficient of friction
_____ and _____ cause the change in the shape or motion of an object
- gravity
- friction
- Acts even at a distance
- Strength of the force is dependent on the distance between the objects and mass
- Reduced by decreasing the masses of objects and /or increasing the distance between them
- Directed toward the center of the object
gravity
- Present only when the two surfaces are in contact
- Depends on the nature and roughness of the surface in contact and masses of objects rubbing each other
- Reduced by lubricants and improving the smoothness of the rubbing surfaces
- Direction is opposite the direction of the motion of the object and perpendicular to the surface of contact
friction
an object or body thrown with an initial velocity and whose motion is influenced by the pull of gravity
projectile
Objects that are initially thrown horizontally in space will be acted upon by gravity thus will move in x and y directions simultaneously.
projectile motion
path of the projectile
trajectory
2 types of motion determined by trajectory
- vertical motion
- horizontal motion
an object travelling in a circle at constant speed is said to be undergoing a _______
uniform circular motion
time required for an object to make one complete revolution
period
number of revolutions completed by the object in a given time
frequency
device which separates the lighter and heavier substances in a mixture
centrifuge
suggests that the force of gravity acting between any two objects is inversely proportional to the square of the separation distance between the object’s center
inverse square law
German astrologer who preceded Newton’s law of gravitation
Johannes Kepler
Kepler’s laws of planetary motion
- law of orbits
- law of areas
- law of periods
“The planet then follows the ellipse in its orbit, which means that the Earth-Sun distance is constantly changing as the planet earth goes around its orbit”
law of orbits
point of nearest approach of the planet to the Sun
perihelion
point of greatest separation
aphelion
By Kepler’s ____ law, the planet moves fastest when it is near perihelion and slowest when it is near aphelion
second (Law of Areas)
Kepler’s ____ Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit.
third (Law of Periods)
