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Gravity
Terms in this set (59)
Define: 'Translational Motion'
'Translational motion' is the movement of an object through space without turning/rotation
Name the 3 key vectors, often used to describe translational motion
Displacement
Velocity
Acceleration
Define: 'Displacement'
'Displacement' is ...
Scalars have ...
a) direction only
b) both magnitude and direction
c) magnitude only
a), scalars have magnitude only
Vectors have ...
a) magnitude only
b) direction only
c) both magnitude and direction
c), vectors have both magnitude and direction
Trigonometric identity #1:
sin^2(x) + cos^2(x) = ?
sin^2(x) + cos^2(x) = 1
Trigonometric identity #2:
sin (2x) = ?
sin (2x) = 2 sin(x)cos(x)
[Trigonometry] at 30 degrees angle, what are sin, cos & tan?
30 degrees angle:
sin (30) = 1/2
cos (30) = ROOT(3)/2
tan (3) = 1/ROOT(3)
[Trigonometry] at 45 degrees angle, what are sin, cos & tan?
45 degrees angle:
sin (45) = 1/ROOT(2)
cos (45) = 1/ROOT(2)
tan (45) = 1
Which of the followings is NOT a vector?
a) Displacement
b) Speed
c) Velocity
d) None of the above
b) - Speed is a scalar, only magnitude without a direction
[T/F] All scalar quantities are always positive
True.
All scalar quantities are always positive.
Instantaneous velocity is the ____ of the graph 'displacement vs. time' at that time.
a) area under the curve
b) slope
c) y-intercept
d) x-intercept
Instantaneous velocity is the [slope] of the graph 'displacement vs. time' at that time.
The magnitude of the velocity decreases if ...:
a) the vector velocity & the vector acceleration have the opposite directions
b) a) the vector velocity & the vector acceleration have the same directions
a) - The magnitude of the velocity decreases if ... the VECTOR velocity & the VECTOR acceleration have the OPPOSITE directions
[Formula] of the acceleration?
a = v/t
[Formula] of the average acceleration?
average a = (change in velocity)/(change in time)
[Name] negative acceleration
decelaration
Displacement is the _____ in a 'velocity vs. time' graph.
a) slope
b) area under the curve/graph
Displacement is the [area under the curve/graph] in a 'velocity vs. time' graph
[Formula] the total displacement of uniformly accelerated motion.
s = x.o + (v.o
t) + (0.5
a*t^2), where:
x.o is the initial displacement
(v.o*t) is the displacement due to initial velocity at time (t).
(0.5
a
t^2) is the displacement due to acceleration at time (t).
[Formula] two other kinematic formula, except the total displacement:
1) v = ?, where v is the final velocity
2) v^2 = ?
1) v = v.o + a*t
2) v^2 = v.o^2 + 2
a
x
[DEF] Force is a (vector/scalar) that can cause a ____ to change ____, thus ____.
That is, force is anything that causes a ____ to ____.
Force is a vector that can cause a mass to change velocity, thus motion.
That is, force is anything that causes a mass to accelerate.
[DEF] Mass is a [vector/scalar]; its measure of [____]. That is a measure of capacity that object is to remain motionless or to move w/ a constant velocity (if no net external force upon it).
Mass is a [scalar]; its measure of [inertia]. That is a measure of capacity that object is to remain motionless or to move w/ a constant velocity (if no net external force upon it).
[DEF] Centre of gravity (COG)
Centre of gravity (COG) is the centre of application of all the gravitational forces acting on object. For a uniform object, it is at the half length of the object.
In other words, COG is the point at which the weight of that object is acting downward.
An object is in STABLE equilibrium if ... [2 answers]:
a) the COG is high, relative to the support point/surface
b) the COG is as low as possible
c) any change in orientation will lead to an increase in COG
d) any change in orientation will lead to a decrease in COG
An object is in STABLE equilibrium if b) the COG is as low as possible, & c) any change in orientation will lead to an increase in COG.
An object is in UNSTABLE equilibrium if ... [2 answers]:
a) the COG is high, relative to the support point/surface
b) the COG is as low as possible
c) any change in orientation will lead to an increase in COG
d) any change in orientation will lead to a decrease in COG
An object is in UNSTABLE equilibrium if a) the COG is high, relative to the support point/surface, & d) any change in orientation will lead to a decrease in COG.
[DEF] Weight is a [___] and a (vector/scalar); proportional to the [___] and[____].
Weight is a [force] and a [vector]; proportional to the [mass] and [gravity].
[Formula] Weight, W = ?
W = m*g
State Newton's Second Law, 'SUM(F) = m*g'
Newton's Second Law states that ...:
"sum of all the exterior forces acting upon the centre of mass is equal to the product of the mass by acceleration of its centre of mass"
[Formula] Newton's Second Law, aka the fundamental dynamic relation.
Newton's Second Law:
SUM(F) = m*g
If there is a net force acting upon an object, the object must [____].
If there is a net force acting upon an object, the object must accelerate.
Objects w/ a greater mass (m) require a greater [____] to get it to move w/ increasing speed (that is, [_____]).
Objects w/ a greater mass (m) require a greater [force] to get it to move w/ increasing speed (that is, [acceleration]).
Newton's Third Law states that ....:
New's Third Law:
"For every action, there is an equal & opposite reaction"
According to Newton's Third Law, if one object exerts a force (F) on a second object, the second object ...:
According to Newton's Third Law, if one object exerts a force (F) on a second object, the second object ...:
... exerts a force (F') on the first object, where F' has the same magnitude (that of F) but the opposite direction.
The Law of Gravitation states that ...:
"there is a force of [_____] existing b/w any two bodies of [_______].
The Law of Gravitation states that ...:
"there is a force of [attraction] existing b/w any two bodies of [masses, m1 & m2].
[Formula] The Law of Gravitation
F = ...?
The Law of Gravitation:
F = K(G)
(m1
m2/r^2),
where K(G) is the universal constant of gravitation and r is the distance b/w bodies
[Formula] Free Fall Motion (*hint: derived from Newton's Second Law)
Free Fall Motion:
SUM(F) = m*g
Drag force depends on ...:
a) location on the earth
b) shape & size of an object
c) velocity of an object
d) all of the above
d) - Drag force depends on (a) location on the earth, (b) shape & size of an object, and (c) velocity of an object.
When drag force equals gravitational F, an object reaches a final velocity called:
Terminal velocity
Projectile motion has a vertical component, that is affected by ____, and a horizontal component, that is ____.
Projectile motion has a vertical component, that is affected by [gravity], and a horizontal component, that is [independent of gravity OR constant].
[Formula] initial speed of a vertical component of projectile motion:
V.oy = ?
Initial speed of a vertical component of projection motion:
V.oy = V.o*sin(a)
[Formula] vertical displacement at time (t) in projectile motion:
y = ?
Vertical displacement at time (t) in projectile motion:
y = v.oy
t + 0.5
g*t^2
[Formula] vertical speed at time (t) in projectile motion:
V.y = ?
Vertical speed at time (t) in projectile motion:
V.y = V.oy
t + g
t
[Formula] initial speed of a horizontal component in a projectile motion?
V.ox = ?
Initial speed of a horizontal component in a projectile motion?
V.ox = V.o*cos(a)
[Formula] horizontal displacement at time (t) in projectile motion:
x = ?
Horizontal displacement at time (t) in projectile motion:
x = V.ox*t
[Formula] horizontal speed at time (t) in projectile motion:
V.x = ?
Horizontal speed at time (t) in projectile motion:
V.x = V.ox (constant horizontally in the absence of air resistance).
[Formula] initial velocity of an OBJECT in projectile motion:
V.o = ?
Initial velocity of an OBJECT in projectile motion:
V.o = ROOT(V.ox^2 + V.oy^2)
[Formula] direction of an OBJECT in projectile motion:
Direction (a) = ?
[Formula] direction of an OBJECT in projectile motion:
Direction (a) = tan(a) = V.oy/V.ox
[Formula] velocity of an OBJECT at time (t) in projectile motion:
V.object = ?
Velocity of an OBJECT at time (t) in projectile motion:
V.object = ROOT(V.y^2 + V.x^2) at any given t
[Formula] the range of projectile motion:
Range =
Range of projectile motion:
Range, x = [V.o^2*sin(2a)]/g
The maximum range of an object in projectile motion can be achieved at what angle?
The maximum range of projectile motion can be achieved at 45 degrees.
Frictional force is a (mechanical/kinetic) energy which is (conservative/non-conservative).
Frictional force is a [mechanical] energy which is [non-conservative].
Frictional forces always oppose the ____.
Frictional forces always oppose the [motion].
[Formula] the maximum frictional force:
f.max = ?
The maximum frictional force:
f.max = u*N, where u is coefficient of friction and N is normal force to the surface.
Normal force (in frictional force) always acts _______ to the surface.
Normal force (in frictional force) always acts [perpendicular] to the surface.
Static friction is when the object is ___ ___, and it must be overcome for _____ to begin.
Static friction is when the object is [not] [moving], and it must be overcome for [motion] to begin.
[Formula] the coefficient of static friction:
u.s = ?
The coefficient of static friction:
u.s = tan (a), where a is the angle at which the object first begins to move on an inclined plane.
The coefficient of kinetic friction, u.k, exists when surfaces are __ ____; and always (greater/smaller) than u.s (the coefficient of static friction).
The coefficient of kinetic friction, u.k, exists when surfaces are [in] [motion]; and always [smaller] than u.s (the coefficient of static friction).
[Formula] Conversation of Energy
E.T = E.k + E.p
[DEF] Equipotential lines
lines of EQAUL voltage (absolute potential);
perpendicular to the electric field lines
[FORMU] Work done by a charge to move between equipotential lines
W = q(V2-V1) or q(PD).
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