Kinematics Flashcards
Define distance:
Distance “d” is the the total length covered by an object between two points. It is a scalar quantity. The SI unit is meter (m).
Define displacement:
Displacement “s” is the shortest distance between any two points or distance in a specified direction. It is a vector quantity. SI unit is meter (m).
Define Speed:
Speed is the total distance travelled per unit of time or rate of change of distance. It is a scalar quantity. v=d/t. hence speed’s unit is (m/s).
Define average speed:
Average speed (Vav) is the total distance travelled divided by total time taken.
Vav= V+U/2
where u=Initial speed/Velocity and V=Final Speed/Velocity
Define velocity:
Velocity is the rate of change of displacement of an object OR displacement per unit time. It is a vector quantity.
V=s/t = Δs/Δt = ds/dt
measured in m/s
Define average velocity:
Average Velocity (Vav) is the total displacement divided by total time taken.
Define uniform velocity:
Uniform velocity means Rate of change of displacement is constant. There is no change in magnitude or direction of velocity.
Define acceleration:
Acceleration is defined as the rate of change of velocity of an object.
a=v-u/t
(m/s^2)
Define uniform acceleration:
Uniform acceleration means rate of change of velocity is constant.
What is the first equation of motion?
v=u+at
What is the second equation of motion?
s=ut + 1/2at^2
What is the third equation of motion?
v^2-u^2=2as
What is the value of acceleration due to gravity?
9.81
Define thinking distance:
Thinking distance is the distance travelled by the car during the reaction time of the driver before he applies the brakes. We assume speed and reaction time remains constant.
Define breaking distance:
Breaking distance is the distance travelled by the car when the brakes are applied and the car comes to rest. Deceleration of the car remains constant.
What is the thinking distance formula?
S1= U x T
where t=reaction time and u=Initial velocity
What is the relationship between thinking distance and initial velocity?
S1 ∝ U
(directly proportional)
What are the factors affecting thinking distance/reaction time?
Driver is not alert/Use of mobile
Intoxication/Drowsiness
Age factor/Eyesight/Fog/Unclear vision
What is the braking distance formula?
v^2-u^2 = 2as
-u^2= 2 (-a) s
-s=u^2/2a
where u=initial velocity v=final velocity and a=deceleration
what is the relationship between braking distance and initial velocity?
S ∝ U^2
s is directly proportional to initial velocity