Topic 3 Kinematics Flashcards
Distance
distance travelled
scalar quantity
Displacement
distance moved by an object in a particular direction
vector quantity
Speed
the rate at which an object moves/ the rate at which distance is covered by an object.
v= d/t
scalar quantity
instantaneous speed
speed at a particular moment
calculated by drawing a tangent on the graph
velocity
speed in a particular direction
vector quantity
v= s/t where s= change in displacement
t= time taken
v= velocity- ms^-1acceleration
the rate at which the object’s velocity is changing
vector quantity
a= change in velocity/ time taken
a= (v-u)/t
how is displacement calculated using a velocity-time graph?
the area under the graph
state what the gradients of the following graphs represent:
1- distance-time
2- displacement- time
3- velocity-time
speed
velocity
acceleration
state the equations of motion that represent an object in uniform acceleration
v= u + at s= (v+u)/2 * t s= ut + (at^2)/2 v^2 = u^2 + 2as
the time for a projectile motion is determined by what?
vertical motion / vertical component of velocity
what is the acceleration of free fall ?
9.81 m/s^2
what is the range of a projectile?
it is the horizontal distance a projectile covers before it reaches the ground.
how can the maximum range be achieved?
by throwing the projectile at an angle of 45 to the horizontal.
Quadratic equation
ax^2 + bx + c = 0
x= (-b +/- square root b^2 - 4ac)/ 2a
horizontal distance
horizontal velocity component * time taken
horizontal velocity component
vcosO where v= initial velocity
O= angle to the vertical
vertical velocity
vsinO where v= initial velocity
O= angle to the vertical
what is the shape of the path of a projectile ?
Parabola
state four different ways to measure speed
using: 2 light gates 1 light gate ticker timer motion sensor
which two methods are use to calculate the average speed.
2 or 1 light gate method
which two methods are used to investigate motion of a moving object
ticker-timer and motion sensor
how to calculate the initial and final velocity of the ‘interrupt’ card when measuring acceleration in a laboratory using a light gate?
u= l1/ t2-t1 where l1= length of the first section of the
interrupt card
t1= instant at which the card
section touched the light gate
t2= instant at which the card section
exited the light gate.
v= l2/ t4 - t3 where l2= length of the second section of
the interrupt card
which method to calculate acceleration gives us an average value of a? and why?
light gate method - because v and u are average value. for the acceleration to be accurate, we would need instantaneous values of v and u.
how to use the ticker-timer to calculate acceleration of an object ?
the practical arrangement is the same as for to measure its speed, i.e, the tape is connected to the trolley.
to interpret the tape we would need to divide the tape into sections, get average velocities of these sections and plot a graph of the velocity values to find the object’s acceleration.
what is used to measure the acceleration of a free falling object?
it can be measured using an electronic timer, ticker-timer and a light gate.
what are the equipment to measure acceleration using an electronic timer?
a stand, electromagnet, ball bearing, trapdoor, electronic timer.
why may there be errors in the result while measuring acceleration of a free falling object?
using an electronic timer:
the electromagnet may gain some magnetism even when its turned off, this could slow down the ball’s fall and consequently disturb the results.
there may also be a mistake while measuring the height of the fall.
using a ticker-timer:
the friction between tape and ticker-timer may slow down the ball’s fall.
