Ch. 1-4

Question 1

Displacement

Answer 1

△X = Xfinal-Xinitial

Question 2

Average Speed

Answer 2

path length/elapsed time

Question 3

Average Velacity

Answer 3

△x/△t

Question 4

Instantaneous Velocity

Answer 4

lim (x–> 0) △x/△t

Question 5

Acceleration

Answer 5

△v / △t

Question 6

Equation for velocity with constant acceleration

Answer 6

v = v initial + at

Question 7

Equation for △x with constant acceleration

Answer 7

△x = 1/2 (v initial + v) t
△x = v initial t + 1/2at^2

Question 8

Equation for velocity squared with constant acceleration

Answer 8

v^2 = v initial ^2 + 2a△x

Question 9

Freely Falling Objects

Answer 9

set acceleration = -9.8 m/s^2 (this is the acceleration of gravity)

Question 10

Components of a Vector

Answer 10

Ax = Acos ⍬ 
Ay = Asin ⍬

Question 11

Magnitude and Direction of a Vector

Answer 11

Magnitude = sqrt (Ax^2 + Ay^2)
Direction = tan ⍬ = Ay/Ax

Question 12

Adding Vectors

Answer 12

draw A, then draw B with the tail of B starting at the tip of A; resultant vector R is drawn from the tail of A to the tip of B;

Rx = Ax + Bx
Ry = Ay + By

Question 13

Negative of a Vector

Answer 13

the vector that gives zero when added to the original vector; opposite directions

Question 14

Subtracting Vectors

Answer 14

simply add the negative of the vector you are trying to subtract

Question 15

In the x- direction, when ax is constant, what equations describe motion?

Answer 15

Vx = V initialx + a(x)t
△x = v initial(x) t + 1/2a(x)t^2
v(x)^2 = v initial(x)^2 + 2a(x) △x

Question 16

In the y-direction, what equations describe motion?

Answer 16

v(y) = v initial (y) + a(y)t
△y = v initial (y) t + 1/2a(y)t^2
v(y)^2 = v initial (y)^2 + 2a(y) △y

Question 17

relative velocity

Answer 17

let E be an observer (at the origin of a graph) and let two objects that are moving be A and B and introduce vector notation:
vector R (AE) = position of Car A as measured by E
vector R (BE) = position of Car B as measured by E
vector R (AB) = position of Car A as measured by car B
r (AB) = r(AE) - r(BE)
v(AB) = v (AE) - v(BE)

Question 18

Newton’s First Law

Answer 18

an object moves with a velocity that is constant in magnitude and direction unless a non-zero net force acts on it

Question 19

Inertia

Answer 19

the tendency of an object to continue in its original state of motion

Question 20

Mass

Answer 20

a measure of the object’s resistance to changes in its motion

Question 21

Newton’s Second Law

Answer 21

the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass

Question 22

Force Vector

Answer 22

F = ma

measured in Newtons (kg x m/ sec^2)

Question 23

Gravitational Force

Answer 23

Fg = G(m1m2/r^2)

Question 24

Weight

Answer 24

w = mg

Question 25

Newton’s Third Law

Answer 25

If object 1 and object 2 interact, the force F(12) exerted by object 1 on object 2 is equal in magnitude but opposite in direction to the force F (21) exerted by object 2 on object 1

Question 26

Normal Force when Stationary

Answer 26

n = mg

Question 27

Objects in Equilibrium

Answer 27

summation of Force = 0

Question 28

Accelerating Objects

Answer 28

use Newton’s second law ( F=ma);

Question 29

Forces of Friction

Answer 29

static friction = coeff of static f x n

kinetic friction = coeff of kinetic f x n

Question 30

Movement in X direction when projectile is close to earth

Answer 30

vx = v xi = vcosθ
Δx = v xi t = (vcosθ)t

Question 31

Movement in Y direction when projectile is close to earth

Answer 31

vy = v = vsinθ - gt
Δy=(vsinθ)t - 1/2gt^2
v^2 = (vsinθ)^2 - 2gΔy