Projectile Motion And Forces Pressure, Density Flashcards
Projectile motion is:
Refers to an object that is in flight after bring thrown or projected.
Acceleration in projectile motion :
Acting in vertical direction which is acceleration due to gravity
No acceleration in horizontal direction hence constant speed.
To find vertical and horizontal components :
Use equations of motion separately applied in x and y axes to get unknown parameters
Vertical component of velocity _ going up the parabola, at _ point of path becomes _
Decreases
Highest
0
Angle between velocity (horizontal) and acceleration (due to gravity) at highest point is
90°
Gravitational field:
Provides force of attraction between masses
Uniform gravitational field :
Field lines parallel, same distance apart
Force depends on _ and _ which vary with planet
Mass and strength of gravitational field
Electric field:
Provides force of attraction/repulsion between charges
Fields equations :
F=mg, g is gravitational field strength
F=Eq, E is electric field strength as
Force depends on _ and _ (electric)
Size of charge and strength of E
Similarities between G and E fields
- point charges and masses follow inverse square law
- non contact forces ie exert force from distance
- field strength defined in terms of force per unit N/kg or C
Differences between G and E fields
- G can only be attractive while E be both attractive and repulsive
- objects can be shielded from E but not G
- E only act upon charted masses, G on all masses
What is upthrust
Force which pushes upwards on a object submerged in fluid ie liquid or gas
Upthrust is due to
Difference in hydrostatic pressure at top and bottom of immersed object
Upthrust/buoyancy is _ in liquid that gases, because _
Larger
Liquids are more dense
Upthrust/buoyancy is _ in liquid that gases, because _
Larger
Liquids are more dense
Hydrostatic pressure depends on _ that an object is submerged in from _. This means
Height/depth
P=pgh
Water pressure at bottom is greater than at top
Explain what happens for upthrust
Upthrust is directly proportional to pressure. Force at bottom will be greater than at top. Resultant pressure causes resultant upward force on object called upthrust
Object rises in fluid when _. Objects float when _
Upthrust is greater than weight
Objects density less than that of fluid
Upthrust is influenced by _ not _
Pressure
Not density
Drag force is
Force acting the opposite direction to an object moving through fluid
Key component of drag :
Increase with speed
Centre of gravity
Point at which weight of object may be considered to act (seems)