Science : Systems in action Flashcards
(119 cards)
1
Q
What is the definition of a system
A
A system is a group of parts that work together to perform a desired task. For example a car is a system; the parts of a car work together to transport you and your cargo
2
Q
What are the two different systems
A
physical and social
3
Q
name a example for a physical system
A
car , clock, phone, bike
4
Q
name a example of a social sytem
A
Educational , political
5
Q
Define social systems
A
Social systems are systems made up of people or organisms.
6
Q
Define physical systems
A
Physical systems are sytems made up of physical parts that you can see and touch
7
Q
Define input
A
Inputs are all of the things that go into a system to make it work (force, energy, resources).
8
Q
Define output
A
Outputs are all of the tasks or services that the system performs (desired force, work, service).
9
Q
Input is also known as the _________
A
Effort
10
Q
Output is also known as the _________
A
load
11
Q
What is Mass
A
The quantity of matter in an object
12
Q
what is weight
A
A measure of the gravitational force on an object
13
Q
is MASS constant anywhere in the universe
A
Yes
14
Q
is Weight constant anywhere in the universe
A
No
15
Q
How do you measure MASS
A
with an equal arm balance , triple beam balance or a pan balance
16
Q
How do you measure WEIGHT
A
with a spring scale
17
Q
What are the units for MASS
A
Grams (g) or kilograms (kg)
18
Q
What is the unit for WEIGHT
A
Newtons (N) (capitalized)
19
Q
When given the mass of an object, you can calculate the weight using the following formula:
A
Fg = mg
20
Q
Fill in the formula for this equation
m = 50 kg g = 9.8 N/kg
Fg =mg
A
Fg = mg
= (50 kg) (9.8 N/kg)
= 490.0 N
21
Q
Is this question correct or incorect if incorect why
“Oh no!” Sayed shouted. “I’ve gained! Last week I weighed 46 kg, now I weigh 48 kg!
A
Incorrect. Change kg to N.
22
Q
An object of 200 N on the surface of the Earth should be an object of fewer Newtons on a space station above the Earth.
A
correct
23
Q
In the space station, I would use a spring scale to find the mass of an object
A
Incorrect. Change mass to weight, or change spring scale to balance.
24
Q
Lily placed a football on one pan of an equal arm balance and got perfect balance with 250 g on the other pan. She would expect to see the same result on the Moon’s surface.
A
Correct.
25
“What’s weight?” the teacher asked. Melinah piped up: “The amount of stuff in something
Incorrect. Change weight to mass.
26
If I go far enough from the Earth’s surface, I will get to a place where my mass will be almost zero
Incorrect. Change mass to weight.
27
On the surface of the Moon, the weight of 100 g of mass would be between 0.1 N and 0.2 N.
Correct.
28
Food is sold in the supermarket by mass – for example, $2.50 for a kg of sugar.
Correct.
29
The butcher weighed the turkey on her “honest weight” spring scales. “Here you are, sir. Your turkey weighs 8.2 kg”
Incorrect. Change kg to N.
30
Mrs. Thomas weighs herself on her scale every morning (then promptly throws it out the window)
Incorrect. Change weighs to finds her mass
31
The following mass is located on Earth. Calculate the weight using the five steps ( earths gravitational pull =9.8 N/kg)
25 kg
m = 25 kg g = 9.8 N/kg
Fg = mg = 25kg x 9.8N/kg
= 245.0 N
Therefore, 25 kg weighs 245.0 N.
32
The following mass is located on Earth. Calculate the weight using the five steps ( earths gravitational pull =9.8 N/kg)
40 kg kg
m = 40 kg g = 9.8 N/kg
Fg = mg = 40kg x 9.8N/kg
= 392.0 N
Therefore, 25 kg weighs 392.0 N.
33
The following mass is located on Earth. Calculate the weight using the five steps ( earths gravitational pull =9.8 N/kg)
150 kg
m = 150 kg g = 9.8 N/kg
Fg = mg = 150kg x 9.8N/kg
= 1470.0 N
Therefore, 25 kg weighs 1470.0 N.
34
An object has a mass of 5.0 kg on the surface of the moon. What would the object’s mass be on Earth?
The object’s mass would still be 5.0 kg because mass is constant in the universe.
35
Define “force”. State the correct units for measuring force.
A force is a push or a pull. It is measured in Newtons.
35
What are the two categories of force? Give an example of a force for each category.
The two types of forces are: Contact force, ex. pushing open a door, and At-a-distance force, ex. gravity.
36
What force causes a sliding object to slow down?
Friction causes a sliding object to slow down.
37
Did you practice science math and word problems today
YES :)
38
What device is commonly used to measure force?
A spring scale is used to measure force.
39
Explain how weight is different from mass.
M)The amount of matter in an object.
W)The gravitational pull on an object.
M)Measured using a balance.
W)Measured using a spring scale.
M)Units are: g or kg
W)Units are: N
M)Constant in the universe.
W)Changes depending on where you are in the universe.
40
define Energy
The ability to do work
41
Define Work
Work is the transfer of energy, by a force acting on an object as it is displaced
42
Makaila lifted a 10 kg book up to a shelf 4 m off the ground, how much work did she do? This is a TWO step question. First you change the mass to a weight (how to do this is on the first worksheet we worked on), then you calculate the work. This question would be worth 9 marks, 4 marks for the first part (no therefore statement) and 5 marks for the second half.
m = 10 kg fg = mg = 10 kg x 9.8 N/kg = 98.0 N
g = 9.8 N/kg
F = 98.0 N W = F x d = 98.0 N x 4 m = 392.0 J
d = 4 m
Therefore she did 392.0 J of work.
43
1. It took Bella a lot of effort to pick up her schoolbag this morning (because she actually does her homework, so there were real books in it). If the bag weighed 5 N and her shoulder is 1.5m off the ground, how much work did she do?
F = 5 N W=Fd = 5 N x 1.5 m = 7.5 J Therefore, she did 7.5 J of work.
d = 1.5 m
44
Victoria did 20 J of work using a 0.5 N force to throw a ball straight to Nicole. How far away was Nicole standing?
W = 20 J d = W F = 20 J 0.5 N = 40.0 m Therefore, Nicole was 40.0m
F = 0.5 N away.
44
At St. Paul’s, the distance between floors is 4m. The elevator in the school weighs 1000 N. Two teachers each weighing 500 N get in the elevator at the ground floor. The elevator goes up two floors and one teacher gets out. The elevator then goes up two more floors and the other teacher gets out. How much work was done by the elevator in total?
F = 1000 N + 500 N x 2 = 2000 N
d = 4 m x 2 = 8 m W = F x d = 2000 N x 8 m = 16,000 J
F = 1000 N = 500 N = 1500 N
d = 4 m x 2 = 8 m W = f x d = 1500 N x 8 m = 12,000 J
Therefore, the elevator did 28,000 J of work.
45
what is an example of a lever
seesaw
46
what is an example of a screw
light bulb
47
what is an example of a pully
blinds
48
Give three examples of a class one lever
Scissors,crow bar, see saw
49
Give three examples of a class two lever
Wheel barrel, staplers, bottle opener, nutcracker
50
Give three examples of a class three lever
Tweezers, tennis racket, hockey stick, sports equipment
51
What is the fulcrum also known as
Pivot point
52
True or false "the closer the load is to the fulcrum the easier it is to move
True
53
Class three levers always make things harder but...
You get an advantage in speed distance and accuracy
54
What is input force
The force applied to a machine
55
What is the difference between input and input force
Input is things that go into a system to make it work and input force is the force applied to the machine
56
What are two examples of machines with a MA of 1
Single fixed pulley, and see saw
57
give me an example of a wheel and axle
door knob
58
give me an example of a wedge
knife
59
give me an example of an inclinded plane
ramp
60
A sloping surface is an ________
inclined plane
61
A bar pivoting on a fixed point is a ________
lever
61
A rope over a wheel is a ________
pully
62
A Wheel conected to a shaft is a ____________
wheel and axle
63
a spiral inclined plane is a ______
screw
64
A slope tappering to a sharp is a _____________
wedge
65
Define action at a distance
Can push or pull an object without touching it
66
define contact force
must touch the object they push or pull
67
__________have two conected levers that can be used to _______paper or cloth
scissors , cut
68
A ________ is a simple machine that uses two hands as the ____________ and ___________ of a lever to move dirt
Shovel, effort, fulcrum
69
In second class levers, the _________is between the effort and _________-
load, fulcrum
70
When the fulcrum is closer to the effort than to the load there is a loss in ______ but a ________ in distance , speed , accuracy.
Easyness , increase
71
What are the three elements of a lever
Fulcrum (pivot point) load(output force) effort (input force)
72
What's the definition of the load?
What the lever is exerting force on (output force)
73
What's the definition of the fulcrum
Where the lever pivots
74
What's the definition of the effort
The force you put on the lever ( input force)
75
In which type of lever are the load and the effort moving in opposite directions
Class 1
76
What is the difference between Input force and output force
Input force is the force applied to the machine and output force is the force applied by the machine to the object
77
What is the definition of friction
A force that opposes the motion of an object
78
What is the definition of kinetic energy
Things in motion
79
What is the definition of potential energy
Stored energy in an object
80
In a class one lever where is the fulcrum
In the middle
81
In class two levers where is the fulcrum
On one edge
82
In class three levers where is the effort
In the middle
83
What is the definition of a machine
Any mechanical system that refuses the force required to accomplish work
84
What does friction produse
Heat energy
85
True of false " rough materials have more friction and heat then smooth surfaces
True
86
What's the formula for calculating PE
PE=Wout/Win x100
PE=MA/IMA x 100
87
What is the unit for percent efficiency
The unit is (%)
88
what are two examples of a machine with a MA greater than one
bike wheels, light bulb
89
what are two examples of a machine with a MA less than one
hockey stick, tennis racket
90
why might someone want a machine to have a MA less than one
to increse speed distance and accuracy
91
define Load force
The force exerted by the load.
92
define effort force
The force required to move the load.
93
define Load arm (output arm):
The distance from the fulcrum to the load.
94
Effort arm (input arm):
The distance from the fulcrum to the effort.
95
When a driver wants to stop a vehicle, ___ between the tires and the ___ helps stop the car.
friction,brakes
96
___ materials produce more friction and ___ than hard materials.
Soft,heat
97
Rough surfaces produce more ___ and __ than ___ surfaces.
friction, heat, smooth
98
Walking on ___ is difficult because the smooth, glassy surface generates little ___.
ice,friction
99
Tell which situation of the two will produce the larger amount of friction:
writing with chalk or pencil
Writing with chalk produces more friction because it is a rougher surface and there is more surface area in contact (so more rubbing).
100
Tell which situation of the two will produce the larger amount of friction:
pushing a light or a heavy box
Pushing a heavy box produces more friction because the surfaces rub together with more force.
101
What are some ways friction can help us?
Friction between our shoes and the ground stops us from slipping. Friction between the tires and the road stops cars from skidding. Friction between the tires and brakes helps stop vehicles. Friction is great for starting a fire too.
102
What are two ways to increase friction on wet or icy roads?
Put salt or sand on the road. Use winter tires with better grip.
103
Ways that we can reduce friction are:
Use rollers or wheels.
Use smooth surfaces.
Lubricate surfaces. (ex. oil)
104
How does the use of a lubricant reduce friction?
Lubricant makes the surface smoother so there is less friction.
105
Why does friction reduce a machine's efficiency?
It wastes some of the input force (effort) and creates heat instead of output force. It causes you to have to use more force than necessary.
106
Why can friction be dangerous?
It could produce too much heat, or damage the machinery.
107
Just to read
Levers are simple mechanisms that make it easier or faster to move something. All levers have a fulcrum (pivot point), an output force (the force exerted by the load), and an input force (the force required to move the load).
:)
108
why does MA have no units
Because its a ratio between two numbers both measured in Newtons
109
True or false the best machine in the world has a PE of 100%
False
110
Why is it impossible to have a machine with a PE of 100%
there will always be friction stealing your input force.
111
As you add more pulleys to a machine the higher the PE and MA get at what point does the number of pulleys stop effecting this
4 pulleys
112
A pulley has a mechanical advantage of 1. What does this tell you about the size and direction of the input and output forces?
The size of the forces is the SAME and the direction is OPPOSITE. Ex. A seesaw.
113
Name a machine with two inputs and two out puts state them
Can opener:
input squeeze lever
Output:holding the can
Input: twist wheel and axle
Output :cutting can
114
Name one example of an output and input for a physical system and a social system
Physical phone : input -electrisity
Output- music
Social educational system:input- people
Output- smart people
115
As you add more pulleys to a system the distance of rope you pull gets _______ and you need to put in _____ force
Longer, less
116
What is the acronym for the 6 simple machines
Lipsww
