Kinematics Flashcards
Define Kinematics
The word “kinematics” comes from a Greek word meaning motion. It is defined as the study of motion without considering its causes.
define rest?
when the position of a body with respect to its surroundings does not change with time it is said to be “at rest”.
define motion?
when the position of a body with respect to its surroundings changes with time it is said to be in motion.
what are the types of motion?
3
Translatory
Rotatory
Vibratory
types of translatory motion?
3
rectilinear motion (linear)
curvilinear motion (circular)
random motion
translatory motion?
Translatory motion is the change in the position of a body as a whole.
In translational motion, a body moves in a path without any rotation.
The path of motion could be straight, curved, or random.
rectilinear motion? Examples?
The straight-line motion of a body is known as its linear motion.
Examples: 1 a car moving in a straight line on a level road.
2 Airplanes flying straight in air.
3 objects falling vertically down.
4 A train moving on a straight track.
Circular motion? Eg?
the motion of an object in a circular or curved path is known as curvilinear motion.
Examples:
1 Ferris wheel moving in a circular path
2 motion of Earth around the Sun
3 Motion of the moon around the Earth.
4 roller coaster
5 movement of a snake
random motion
the irregular and disordered motion of an object is called random motion. It is when an object changes its direction frequently. It is also called zig-zag motion or irregular motion.
1 motion of flying mosquitoes
2 motion of birds in the sky
3 motion of dust particles in the air
4 the Brownian motion of liquid and gas molecules along a zig-zag path.
Rotatory motion?
The spinning motion of a body about its axis is called a rotatory motion. In other words, the rotation of a body around a fixed rotation axis.
Examples:
1 motion of a top
2 motion of wheel about its axis
3 motion of Earth around its geographic axis.
4 motion of steering wheel
5 motion of the ball at the tip of a finger
6 motion of helicopter rotors
7 motion of blades of fan
vibratory motion?
the to and fro motion of an object about its mean position is known as vibratory motion.
Examples:
1 motion of a simple pendulum
2 motion of string of sitar
3 motion of a cradle
4 motion of see-saw
5 The vibrational motion of mobile phones.
6 When sound enters our ears, our eardrum vibrates.
what is the mean position?
Mean/Equilibrium Position
It is a position of the body when the net force acting on it is zero.
what is an axis?
An axis is an invisible line around which an object rotates or spins.
what are scalars?
Physical quantities that can be completely described only by its magnitude with the proper unit are termed scalar quantities or simply scalars.
what are vectors?
Physical quantities that can be completely described by its magnitude and direction are termed vector quantities or simply vectors.
examples of vectors?
velocity, force, acceleration, weight, displacement and pressure etc.
examples of scalars?
density, energy, volume, electric current, time and speed etc.
what is position?
the location of a place or a point with respect to a reference point called origin.
what is a position vector?
a vector that symbolizes the position or location of any given point with respect to any arbitrary reference point.
arbitrary: chosen without specific rules or restrictions
what is the distance?
length of a path between two points is called the distance.
Distance is measured in meters.
Distance is a scalar quantity.
what is displacement?
the shortest distance from the initial position to the final position is called displacement.
It is a vector quantity
measured in meters
It is represented by d.
is displacement vector or scalar?
vector
symbol for displacement?
d
symbol for speed?
v
the symbol for velocity
lowercase v
the symbol for distance?
s
what is speed?
the distance covered by an object in unit time is called its speed
2 things to know the speed of an object
distance travelled
time taken to complete that distance
what is velocity?
the rate of displacement of a body
what is uniform velocity?
a body has uniform velocity if it covers equal displacement in equal intervals of time however the interval may be short.
what is acceleration?
rate of change of velocity of a body.
define uniform acceleration?
if it has equal changes in velocity in equal intervals of time however the interval may be short.
what is -ve acceleration called?
deceleration or retardation
what is negative acceleration?
is the decrease in velocity of a body with time. The direction of negative acceleration is opposite to the direction in which the body is moving.
aka retardation
what is a variable speed?
An object is said to be at variable speed when the object covers UNEQUAL distances at equal intervals of time.
what is the average speed?
total distance (s) covered in total time (t).
the formula for velocity?
v=displacement/time
v arrow= d f arrow-d arrow i/ t f - ti
what is average velocity?
is the total displacement (d arrow) covered in total time (t).
what is another word for the gradient?
slope
What is a perpendicular line?
perpendicular lines are two lines that meet or intersect each other at right angles.
how to convert m/s to km/h?
multiply it by 3.6
how to convert km/h to m/s?
multiply by 10/36
change first equation of motion to find acceleration?
Vf=Vi+at
Vf-Vi/t=a
state equations of motion?
1D information is called _______
scalar quantity
magnitude
2D info = vector (magnitude + direction)
what is gravitational acceleration?
acceleration of freely falling bodies. denoted by g
free fall = objects falling only cz of gravitational force
gravity made an object to accelerate.
what does slope of distance-time & speed-time graph tells us?
speed
acceleration
derive 1st 2nd and 3rd equation of motion.
can we accelerate an object without speeding it up or slowing it down?
yes
circular path
speed is constant but direction is changing
change in direction = acceleration
how to convert km/h2 to m/s2
divide it 1296
it is acceleration
how to convert m/s2 to km/h2?
multiply it by 12960/10
12960.
velocity time graph for zero, positive, negative, constant, increasing acceleration.
zero acceleration= constant velocity
