ch 3 - dynamics

Question 1

resultant force =

Answer 1

resultant force = mass * acceleration
F = ma

Question 2

newton’s second law?

Answer 2

. resultant force is proportional or equal to mass*acceleration

. resultant force is proportional or equal to rate of change of momentum of the body

Question 3

what is intertia?

Answer 3

the tendency of an object in motion to remain in motion and object at rest to stay unless an external unbalanced force acts on it

a measure of how difficult it is to change the velocity or speed and direction of an object

measure of mass of an object

greater mass = greater inertia

acceleration inversely proportional to mass

Question 4

what is weight?

Answer 4

the force on an object caused by a gravitational field acting on its mass, doenwards arrow

Question 5

what is friction?

Answer 5

the name for a resistive force when two surfaces are in contact and tending to silde over one another, acts along a surface

Question 6

what is drag?

Answer 6

a resistive force similar to friction, opposes the motion of the object in both air and water, reduced by giving object a streamlined shape

Question 7

what is upthrust?

Answer 7

the upwards forces experienced by any object in the fluid, arises from pressure fluid exerts on an object

deeper = more pressure

if upthrust > object weight, objecy floats

Question 8

what is a contact force/normal force?

Answer 8

a force that pushes up against you weight and give support so you don’t fall down

force than acts at right angles to the surface when two objects meet

Question 9

what is tension?

Answer 9

the force in a rope or string when it is stretched, pulls back to shorten the string or spring

Question 10

what is centre of gravity?

Answer 10

the point where the entire weight of an object appears to act

Question 11

W = mg

Question 12

g moon =

Answer 12

1.6 m s-2

Question 13

g earth =

Answer 13

9.81 m s - 2

Question 14

newton’s first law?

Answer 14

an object remains at rest or travels at constant velocity unless it is acted on by a resultant force

F = ma

Question 15

uniform motion?

Answer 15

the natural state of motion of an object - uniform velocity, constant speed and direction

Question 16

what is a resultant force?

Answer 16

the single force that has the same effect as all of the forces acting on the object

Question 17

what is terminal velocity?

Answer 17

the maximum velocity reached by an object falling under gravity or accelerated by a constant force

Question 18

what is a resistive force?

Answer 18

a backwards force in the opposite direction to movement caused by friction or some other viscous force

Question 19

less drag in air because…

Answer 19

air less dense than water

Question 20

newton’s third law?

Answer 20

whne two bodies interact, the forces they exert on each other are equal in size and opposite in direction

Question 21

what are the characteristics of the forces that make a up a ‘newton’s third law pair’

Answer 21

. act on different objects
. opposite in direction
. equal in magnitude
. forces of the same type

Question 22

forces of the same type can be:

Answer 22

. gravitational forces
. electrical forces
. contact forces
. tension forces
. magnetic forces

Question 23

what are base units?

Answer 23

defined units of the SI system from which all other units are derived

. length = m
. mass = kg
. time = s
. electric current = A
. thermodynamic temperature = K
. amount of substance = mol
. luminous intensity = cd (candela)

Question 24

what are derived units?

Answer 24

unit that are combinations of the base units of then SI system

Question 25

force = (unit )

Answer 25

kg m s-2

Question 26

speed = (unit)

Answer 26

ms - 1

Question 27

what does homogeneous mean?

Answer 27

equations with the same base unit on each side are homogenous

Question 28

kilo

Answer 28

10³ (k)

Question 29

mega

Answer 29

10^6 (M)

Question 30

giga

Answer 30

10^9 (G)

Question 31

tera

Answer 31

10^12 (T)

Question 32

deci

Answer 32

10^-1 (d)

Question 33

centi

Answer 33

10^-2 (c)

Question 34

milli

Answer 34

10^-3 (m)

Question 35

micro

Answer 35

10^-6 (u)

Question 36

nano

Answer 36

10^-9 (n)

Question 37

pico

Answer 37

10^-12 (p)