M3 Kinematics and Linear Motion Flashcards
define speed
give unit
distance per unit time
ms^-1
define velocity
give unit
rate of change of an object’s displacement
ms^-1
define acceleration
give unit
rate of change of an object’s velocity
ms^-2
define displacement
give unit
distance moved in a stated direction
m
define instantaneous speed
speed at any particular moment
define average speed
total distance travelled over a given amount of time
on a displacement-time graph what does it mean if it is a straight diagonal line?
constant velocity
0 acceleration
on a displacement-time graph what does it mean if it is a positive curve
changing velocity
increasing acceleration
on a displacement-time graph what does it mean if it is a negative curve
changing velocity
decreasing acceleration
what is the gradient on a velocity-time graph
the acceleration
on a velocity-time graph what does the area between the graph and the x axis equal
displacement of the object
what are the 2 conditions for SUVAT equations
motion in a straight line
an object moving with a constant acceleration
what does SUVAT stand for and how would you use it in a question
s= displacement u= initial velocity v= final velocity a= acceleration t= time
you fill in all the parts you know from the question and pick one of the four SUVAT equations and work out the asked thing
A stone is thrown off the top of a 24m high cliff. It’s initial velocity is 15ms-1 in the horizontal direction.
1) How long does it take to fall into the sea?
2) What is its range?
3) Find the magnitude and direction of its velocity as it hits the water.
Horizontal / verticle: u = 15 / 0 v = 15 / ? a = 0 / 9.81 t = ? / ? s = ? / 24
1) s= ut + 1/2 at^2
24 = 5t^2
t= 2.2 s
2) s = 0.5(u+v)t
= 1.1 X 30
= 33 m
3) v = u + at = 9.81 X 2.2 = 21.7 ms^-1 use pythag angle = tan^-1(21.7/15) = 55 degrees
how do you deal with a projectile at an angle
resolve the velocity vector into its horizontal and verticle components
Uh = Ucosx Uv = Usinx
in a projectile question what do you SUVAT will be in the horizontal and verticle direction if something is being thrown upwards to the highest point
Horizontal / Verticle S = range / height (m) U = ucosx / usinx (ms^-1) V = ucosx / 0 (ms^-1) A = 0 / -9.81 (ms^-2) T = t / t (s)
define density
give units
mass per unit volume
kgm^-3
A gold block has a density of 19 320 kg m^-3. What is the volume of a 275 g gold block in cm^3?
volume= 0.275/19320=1.42×10^(−5) m^3=14.2 cm^3
Define pressure
force per unit area
What is fluid pressure
An object submerged in a fluid has a pressure that depends on the density of the fluid and the depth of the object.
The denser the fluid, the more particles there are to collide with the object.
The deeper the object, the greater the weight of the particles above the object and so pressure increases with depth.
When does upthrust occur?
when objects are submerged in fluids because the top and bottom of these objects are at different depths and so experience different forces.
what is the equation for upthrust?
upthrust = (h2−h1)ρgA
what is Archimedes principle
When a body is completely or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid that it has displaced.
define free fall
only gravity is acting on an object
the only force acting on an object is weight
in free fall is gravity positive or negative
negative
