PHYS Ch. 1 Kinetics & Dynamics Flashcards
What is the diff b/w scalar and vector?
Vectors are numbers that have direction and magnitude, while scalars have ONLY magnitude
What are vector examples?
displacement, velocity, acceleration, and force
What are scalar examples?
distance, speed, energy, pressure, and mass
How do you find the X and Y intercepts of a triangular vector?
X = vcos0
Y = vsin0
How do you calculate the resultant vector (R)?
R = square root of (X + Y)^2
How do you calculate the direction (d) of the resultant vector?
d = tan^-1 Ry/Rx
What does a +n vs. -n mean?
+n = vectors A and B are in the same direction; -n, they are in opposite direction
What is the equation for velocity?
v = change in x/change in t
x = displacement
t = time
What is the equation for speed?
speed = distance/time
What is the SI unit for force?
Newton (N) = kg*m/s^2
Describe the relationship between height and acceleration due to gravity.
Acceleration due to gravity (g) decreases with height above the Earth and increases the closer one gets to the Earth’s center of mass.
What is the equation for gravitational force (Fg)?
Fg = Gm1m2/r^2
G = 6.67 x 10^-11 Nm^2/kg^2
m1 = mass of object 1
m2 = mass of object 2
r = distance between the 2 objects
What happens to gravitational force when distance is cut in half?
if r is halved, Fg will quadruple
What happens to gravitational force when mass is tripled?
force is tripled
What is the mass of proton and electron?
proton = 1.67 x 10^-27 kg
electron = 9.11 x 10^-31 kg
What is the diff b/w kinetic and static friction?
static friction (fs) exists b/w a stationary object and the surface upon which it rests, whereas kinetic friction (fk) is b/w the sliding object and the surface on which the object slides
What is the equation for weight?
Fg = m*g
m = mass
g = 9.8m/s^2
What is acceleration?
the rate of change of velocity that an object experiences as a result of some applied force
What is the equation of average acceleration?
a = change in velocity/change in time
What does a positive and negative slope mean in a velocity vs. time graph?
positive = acceleration is positive and in the direction of the velocity
negative = the acceleration is negative (deceleration) and in the opposite direction of the velocity
What is Netwon’s first law?
the law of inertia: a body at rest or in motion with constant velocity will remain that way unless a net force acts upon it
What is the equation for Fnet?
Fnet = m*a
Fnet = net force
m = mass
a = acceleration
What is Netwon’s second law?
an object of mass will accelerate when the vector sum of the force results in some nonzero resultant force vector
What is Netwon’s third law?
to every action, there is always an opposite but equal reaction
What are the equations for linear motion?
v = initial velocity + acceleration * time
x = initial velocity * time + acceleration * time squared / 2
velocity squared = initial velocity squared + 2 * acceleration * displacement (x)
x = avg velocity * time
What does air resistance do to an object?
it increases the speed of the object
What are the equations for circular motion?
Fc = mass * velocity squares/ radius
What is the direction of centripetal force in circular motion?
force in a linear direction along the tangent
What is the tangential force in uniform circular motion?
zero because there is no change in the speed of the object
What is the direction of acceleration?
acceleration is always in the direction of the net force
What is sin 90 and 0?
sine 90 = 1
sin 0 = 0
What are the equations for torque?
T = length of level arm * magnitude of the force
T = rFsin(o)
