Force and Motion Flashcards
(Formula of motion)
v = ?
v = u + at
(Formula of motion)
s = ? (no V)
s = ut + ½ at²
(Formula of motion)
s = ? (no a)
s = ½ (u+v)t
(Formula of motion)
v² = ?
v² = u² + 2as
(Formula of motion)
Sn = ?
Sn = Vi + a/2 (2n-1)
(Formula of motion)
What is the sign of g when downward motion vs upward motion
Downward: g
Upward: -g
Newtons First Law
Body will continue to be at rest when no external force acts upon it
Newtons Second Law
Force produces acceleration in direction of force. (a is directly proportional to applied F and inversely proportional to mass)
1N = ___ dyne
10^5 dyne
Newtons Third Law
For every action there is an equal and opposite reaction
Equal and opposite reactions always act on ______. They never _______
Always act on TWO DIFFERENT BODIES . They never CANCEL / NEUTRALIZE THE EFFECT OF FORCE .
(Motion of connected bodies)
F1 =
F2 =
F1 = (m1/m1+m2) F
F2 = (m2/m1+m2) F
P = mv
SI Unit of P?
Another unit?
SI Unit is kgms^-1
Another unit is Ns
Newtons Second Law in terms of momentum
Time rate of change of momentum is equal to the force acting on the body
(F = p/t)
Impulse (J) =
J = Ft
Elastic collision vs Inelastic collision
Elastic = both momentum and KE is conserved
Inelastic = only momentum is conserved. (KE converted to another form)
P1 + P2 = P1’ + P2’
m1u1 + m2u2 = m1v1 + m2v2
Speed of approach = Speed of recession
v1 =
v2 =
v1 = (m1-m2/m1+m2) u1 + (2m/m1+m2) u2
v2 = (2m1/m1+m2) u1 + (m2-m1/m1+m2) u2
Case when masses equal (m1 = m2)
EXCHANGE Vs
v1’ = u2 and v2’ = u1
Case when equal masses, stationary target (u2 = 0)
v1’ = 0
v2’ = u1
(Incident stops moving after collision and target moves with incident’s velocity)
Case when incident heaver than target and target is stationary
(m1»_space; m2) (u2 = 0)
v1 = u1 (Velocity of incident wont change)
v2 = 2u1 (Velocity of target will be twice of incident’s)
Case when target heavier than incident and target is stationary
(m1 «_space;m2) (u2 = 0)
v1 = —u1 (Incident gets pushed back in opposite direction but same velocity)
v2 = 0 (Target remains stationary)
Path of projectile motion is dependent on 2 things:
— Initial velocity (u)
— Forces
(Projectile motion)
Velocity at an instant
Vx = ?
Vy = ?
Vx = Vcosø
Vy = Vsinø - gt
(Projectile motion)
Position at an instant
Sx = ?
Sy = ?
Sx = ucosøt
Sy = usinøt - ½gt²
(Projectile motion)
Height
h = (u² sin² ø / 2g)
(Weird g in height so 2g)
(When 2g then 2 exponents)
(Projectile Motion)
Range
x = (u² sin 2ø / g)
(One g in range so 1 exponent)
(but also 2ø)
(Projectile Motion)
Time
t = (2u sin ø / g)
(Time = Two)
(Projectile Motion)
Max Range
ø = ?º
ø = 45º
R = (v² sin 2(45) / g)
which equals
R = v²/g (because sin 90 = 1)
Rmax = ___H
when how many degrees
Rmax = 4H
when 45º
R = H when?
tan^-1 (4) = ø = 76º
H with respect to T ?
H = gT² / 8
so
T = √(8H/g)
When are ø1 and ø2 the same range?
When complimentary angles
ø1 + ø2 = 90
(Projectile Motion)
When is a = 0
a = 0 on x axis at all times
(Projectile motion)
When is v = 0 ?
v = 0 on y axis at max height
(Projectile Motion)
KE H = ?
KE H = ½ mu² cos² ø
or
KE H = KEinitial cos² ø
(Projectile Motion)
PE = ?
PE = ½mu² sin² ø
(Projectile Motion)
Momentum?
Pu = mucosø
(Projectile Motion)
PE H / KE H = ?
PE H / KE H = tan² ø
