Motion & Newton's Laws & Energy Flashcards
what is v
change in position over time (s/t)
what is speed
how fast the distance is changing every sec
what is acceleration
how fast the velocity is changing e.g. Vf-Vi/t
what is s
straight line distance from start point to end point
s= ut + 1/2(at^2)
what do vectors need
scalar & direction e.g. 15m <– = -15
what is newton’s 1st law
silk table cloth - body will remain at rest / move with constant v unless acted on by a resultant force
what is newton’s 2nd law
F = ma e.g. the resultant force on an object is equal to the rate of change of it’s momentum
what is newton’s 3rd law
equal & opposite force
what is the difference between driving & frictional forces
driving is pushing the object and is +ve, while frictional is resisting it and is -ve
where do gravitational fields point
directly toward the centre of massw
how is gravity measured (units)
N/kg or m/s2
what is kinetic energy
E = 1/2(mv^2)
what is gravitational energy
E = mgh
what is work energy
W = Fs
what is torque
tao (t) = Fr
what are the principles of projectile motion
- symmetrical
- v = 0 at max height
- v for vertical component
- kinetic energy than gravitational energy
what are the principles of circular motion
a = v^2/r
so F = m(v^2/r)
use trig to work out tension
what is the formula for gravitational field strength on earth
g = (G x m)/r^2
where m = planet mass, r = distance from centre of mass
what is the relationship between gravitational strength & distance r
being further away (big r) reduces g
what is the relationship between r & F in torque
inverse, harder to push a door near it’s pivot point, easier further out
what is the formula for elastic energy
E = 1/2* (kx^2)
where x = compression, k = spring constant (N/m)
what is momentum and can newton’s 3rd law apply
p = m*v
yes
what is the formula for impulse momentum
change in p = net F x change in t,
where p = pfinal - pinital
- so it can be -ve
can net force be negative
yes when the object comes to a stop
what is potential energy & it’s diff. to kinetic
energy stored by a field e.g. gravitational, electric or magnetic
e.g. not kinetic because these are particles moving around
what happens when 2 gasses are heated to produce water, gas and energy e.g. CH4 + O2 –> H2O + CO2 + energy
greater PE –> lower PE, more KE and radiation
is radiant energy (light/warmth) kinetic or potential?
both
what is the formula for power
W/change in time
what is the significance of gravitational fields for an object in free fall
acceleration = magnitude of gravity
what is the formula for tension
a = sum of forces/mass of object
gravity is a negative forcce because tension is always pulling, while gravity is pushing
explain horizontal & vertical vector components in projectile motion
horizontal component is constant and only determines how far the ball goes
vertical component changes and becomes shorter as it gets to the peak where gravity kicks in and it becomes 0. then it gets larger again
what is the formula for vertical velocity
v = u + at
in which of the following collisions is momentum conserved - inelastic, elastic, perfectly inelastic
all
in which of the following collisions is kinetic energy conserved - inelastic, elastic, perfectly inelastic
only elastic
in which of the following collisions is potential energy conserved - inelastic, elastic, perfectly inelastic
none, only converted to KE in explosion
in which of the following collisions is thermal energy generated - inelastic, elastic, perfectly inelastic
all except elastic (KE –> THE)
what is an elastic collision
one where no energy is lost
what is an inelastic collision
one where KE is not conserved (transferred to other forms) but momentum is
