PHYS Ch. 1 Kinetics & Dynamics

Question 1

What is the diff b/w scalar and vector?

Answer 1

Vectors are numbers that have direction and magnitude, while scalars have ONLY magnitude

Question 2

What are vector examples?

Answer 2

displacement, velocity, acceleration, and force

Question 3

What are scalar examples?

Answer 3

distance, speed, energy, pressure, and mass

Question 4

How do you find the X and Y intercepts of a triangular vector?

Answer 4

X = vcos0
Y = vsin0

Question 5

How do you calculate the resultant vector (R)?

Answer 5

R = square root of (X + Y)^2

Question 6

How do you calculate the direction (d) of the resultant vector?

Answer 6

d = tan^-1 Ry/Rx

Question 7

What does a +n vs. -n mean?

Answer 7

+n = vectors A and B are in the same direction; -n, they are in opposite direction

Question 8

What is the equation for velocity?

Answer 8

v = change in x/change in t
x = displacement
t = time

Question 9

What is the equation for speed?

Answer 9

speed = distance/time

Question 10

What is the SI unit for force?

Answer 10

Newton (N) = kg*m/s^2

Question 11

Describe the relationship between height and acceleration due to gravity.

Answer 11

Acceleration due to gravity (g) decreases with height above the Earth and increases the closer one gets to the Earth’s center of mass.

Question 12

What is the equation for gravitational force (Fg)?

Answer 12

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

Question 13

What happens to gravitational force when distance is cut in half?

Answer 13

if r is halved, Fg will quadruple

Question 14

What happens to gravitational force when mass is tripled?

Answer 14

force is tripled

Question 15

What is the mass of proton and electron?

Answer 15

proton = 1.67 x 10^-27 kg
electron = 9.11 x 10^-31 kg

Question 16

What is the diff b/w kinetic and static friction?

Answer 16

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

Question 17

What is the equation for weight?

Answer 17

Fg = m*g
m = mass
g = 9.8m/s^2

Question 18

What is acceleration?

Answer 18

the rate of change of velocity that an object experiences as a result of some applied force

Question 19

What is the equation of average acceleration?

Answer 19

a = change in velocity/change in time

Question 20

What does a positive and negative slope mean in a velocity vs. time graph?

Answer 20

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

Question 21

What is Netwon’s first law?

Answer 21

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

Question 22

What is the equation for Fnet?

Answer 22

Fnet = m*a
Fnet = net force
m = mass
a = acceleration

Question 23

What is Netwon’s second law?

Answer 23

an object of mass will accelerate when the vector sum of the force results in some nonzero resultant force vector

Question 24

What is Netwon’s third law?

Answer 24

to every action, there is always an opposite but equal reaction

Question 25

What are the equations for linear motion?

Answer 25

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

Question 26

What does air resistance do to an object?

Answer 26

it increases the speed of the object

Question 27

What are the equations for circular motion?

Answer 27

Fc = mass * velocity squares/ radius

Question 28

What is the direction of centripetal force in circular motion?

Answer 28

force in a linear direction along the tangent

Question 29

What is the tangential force in uniform circular motion?

Answer 29

zero because there is no change in the speed of the object

Question 30

What is the direction of acceleration?

Answer 30

acceleration is always in the direction of the net force

Question 31

What is sin 90 and 0?

Answer 31

sine 90 = 1
sin 0 = 0

Question 32

What are the equations for torque?

Answer 32

T = length of level arm * magnitude of the force
T = rFsin(o)