Kinematics And Dynamics

Question 1

Units of the British Imperial System

Answer 1

Foot, pounds and second

Question 2

Metric system units

Answer 2

Meters, kilograms, seconds -> centimetres, grams, seconds

Question 3

Base units?

Answer 3

Standard units of a measurement system

Question 4

Derived units?

Answer 4

Fusing or associating base units with each other

Ex: Newton - kg m / s^2

Question 5

Vectors?

Answer 5

Values that have both magnitude and direction

Question 6

Scalar?

Answer 6

Value only has magnitude and no direction.

Question 7

Resultant?

Answer 7

Sum of vectors.

Question 8

Tip to tail method?

Answer 8

Method of vector addition:

Tail of B to tip of A -> line obtained is the magnitude of A + B

Question 9

Breaking components?

Answer 9

Method of vector addition:

Vectors broken into horizontal and vertical ie. X and Y / perpendicular and parallel components.

Question 10

How to find components of vector?

Answer 10

X and Y components can be found from V by drawing right triangle using V as hypotenuse. X is adjacent and Y is opposite.

As cos O = adj by hyp and sin O = opp by hyp ->

X = V cos O and Y = V sin O

Question 11

Cos O?

Answer 11

Adjacent by hypotenuse

Question 12

Sin O?

Answer 12

Opposite by hypotenuse

Question 13

How to obtain vector from components?

Answer 13

Tip to tail method -> use Pythagorean theorem to obtain hypotenuse value.

V^2 = X^2 + Y^2

Question 14

How to subtract vectors?

Answer 14

Add vector of equal magnitude but opposite direction/sign to first vector.

A - B = A + (-B)

Question 15

How to multiply vectors and scalars?

Answer 15

• Magnitude will change.
• Value may be anti-parallel (scalar n is -ve) or parallel (n is +ve)
• A*n = B

Question 16

How to multiply two vectors to obtain a scalar value?

Answer 16

Dot product method

A . B = A x B cos 0

Question 17

How to multiply two vectors to obtain a vector?

Answer 17

Cross-product method:

A x B = A x B sin 0

Question 18

How to determine direction of cross product?

Answer 18

C = A x B

Right hand rule - thumb = A, index = B, palm = C

Question 19

What is displacement?

Answer 19

Object in motion experiencing change in position - ie. Displacement (x or d).
Vector quantity, magnitude and direction.
Linearly connects initial and final position - not actual pathway, net change in position.

Question 20

Distance?

Answer 20

Change in position in space.
Scalar, magnitude only.
Considers pathway taken.

Question 21

Velocity?

Answer 21

Vector, magnitude and direction.
Rate of change of displacement in a given unit of time.
SI unit is m/s.
Vector direction same direction displacement.
^X / ^T = V

Question 22

Speed?

Answer 22

Rate of change of distance in a given unit of time.
Scalar quantity.
^D / ^T = V

Question 23

Instantaneous velocity and instantaneous speed?

Answer 23

I speed = I velocity magnitude. I speed is scalar.
I velocity is the average velocity as the change in time approaches zero.

Vi = ^X / ^T
[lim ^T -> 0]

Question 24

Average speed and average velocity?

Answer 24

A speed not always equal to A velocity.
A velocity ratio of X over ^T.
A speed ratio of D over ^T.

Question 25

Force?

Answer 25

Vector quantity. Experienced as pushing or pulling. Exists between objects with a distance in between them. SI unit is Newton ie. kg m / s^2

Question 26

Gravity?

Answer 26

Attractive force felt by all of matter. Fg = Gm1m2 / r^2 G (gravitational constant) = 6.67 x 10 ^-11 Nm^2 / Kg ^2 G inversely proportional r^2. G proportional m1, m2.

Question 27

Friction?

Answer 27

Force opposing movement of object - slowing it down to stationary state. Type: Static friction and kinetic friction.

Question 28

Static friction?

Answer 28

Experienced between stationary object and surface it rests on. (Min) 0 <= fs <= Ms N (Max) Ms = Static friction coefficient N = Normal force Applied force less than threshold will not move object.

Question 29

Kinetic friction?

Answer 29

Force between sliding object and surface it is on. Fk = Mk N Fk is constant. Ms > Mk

Question 30

Mass?

Answer 30

Amount of matter in an object - independent of gravity. Scalar quantity. SI unit is Kg.

Question 31

Weight?

Answer 31

Measure of gravitational force on mass. Vector quantity. SI unit is Newton ie Kg m / s^2 Fg = m g Fg = weight g = 9.8 m/s

Question 32

Centre of mass?

Answer 32

Defined relative to an object or system of objects. Average position of all the parts of the system, weighted according to their masses. X = m1x1 + m2x2 / m1 + m2

Question 33

Acceleration?

Answer 33

Rate of change of velocity of an object due to applied force. Vector quantity. SI unit is m/s^2. If it opposes initial velocity then it causes deceleration. Avg a = ^V / ^T

Question 34

Instantaneous acceleration?

Answer 34

Average acceleration as ^T approaches 0. a = ^V / ^T [lim ^T -> 0]

Question 35

Velocity vs time?

Answer 35

If slope is downwards ie. -ve, a is -ve. If slope is upwards ie. +ve, a is +ve.

Question 36

Newtons 1st law?

Answer 36

A body will remain in rest or constant motion unless a force acts on it. F net = m a = 0

Question 37

Newtons 2nd law?

Answer 37

Object of mass m, will accelerate when vector sum is not equal to 0. F net = m a F and a are in the same direction.

Question 38

Newtons 3rd law?

Answer 38

Every force has an equal and opposite reaction. Fab = -Fba

Question 39

Types of motion?

Answer 39

Constant (no acceleration) or changing (with acceleration).

Question 40

Linear motion?

Answer 40

Velocity and acceleration are in the same line of motion, continuing along same line as object. Linear motion with constant acceleration.

Question 41

Velocity of object in constant motion?

Answer 41

Vf = vi + at

Question 42

What is free fall?

Answer 42

Object falling with constant acceleration due to gravity (g = 9.8m/s^2) and would not reach terminal velocity.

Question 43

What is terminal velocity?

Answer 43

Air resistance opposes object motion, proportionally to object speed - increase in drag force with increase in velocity. When DF = weight of obj, object falls with constant + terminal velocity.

Question 44

Projectile motion?

Answer 44

Motion path of object is 2 dimensional. Velocity and acceleration move independent of each other.

Question 45

Inclined planes?

Answer 45

Motion path of object is 2 dimensional. Force vectors have parallel and perpendicular components (with respect to the plane)

Question 46

Parallel force vector of inclined plane?

Answer 46

Fg = mgsin0

Question 47

Perpendicular force vector of inclined plane?

Answer 47

Fg = mgcos0

Question 48

Circular motion?

Answer 48

Force causes object to move in circular pathway. Hence, displacement of object is 0.

Question 49

Uniform circular motion?

Answer 49

Vinst is tangential to circular path and is kept in path by inward facing centripetal force.

Question 50

Centripetal force?

Answer 50

Has a radial and tangential force (0, no change in speed) components. Generates constant acceleration.

Question 51

Magnitude of centripetal force?

Answer 51

Fc = mv^2/r

Question 52

Translational equilibrium?

Answer 52

Occurs when forces cause object to move with out rotation. They may be linear, parabolic or inclined.

Question 53

Translational equilibrium condition?

Answer 53

Vector sum of forces on an object are zero, ie. 1st condition of equilibrium. Constant velocity, speed and direction.

Question 54

Rotational equilibrium condition?

Answer 54

Forces applied causing object to move around fixed pivot fulcrum at some distance to generate torque which generates rotational motion.

Question 55

Torque?

Answer 55

T = r * F = rFsin0