stud
bud
Sign up
Log in
Home
Library
Explore
SAT
More
Work and Simple Machines Flashcards | StudBud
Explore
/
Work and Simple Machines
Work and Simple Machines
60 terms
·
StudBud Administration
·
59 plays
8th grade chapter 3 Review
Flashcards
60 cards
F
Practice quiz
P
Host live
L
Questions
60
Answers
1
There are two ways to make work easier.
True
False
2
Scissors have
a wedge
a fulcrum
a lever
all fo the above
3
Machines don't change the amount of work you need.
True
False
4
Work is labeled in Watts.
True
False
5
What reduces friction by forming a thin film between moving surfaces?
rocks
sandpaper
potato
lubricant
6
A screw is a wedge.
False
True
7
When can work be done?
when the direction of the force is the same direction of motion
setting a box on the ground
when you hold a box in the air
when the direction of force is different to the direction of motion
8
Which of the following is NOT an inclined plane?
screw
slide
screw
tweezers
9
How do you find joules?
work/time
output work/input work x 100
force x distance
output work/input work
10
The output work done by a machine never exceeds the input work of the machine.
False
True
11
How is the energy of an object affected after work is done on it?
energy remains the same
no energy is left
energy is decreased
energy is increased
12
What is a fulcrum?
a wedge that moves
to do work using only one movement
simple machine that pivots
the point a lever pivots
13
Tim does 16 j of work over 184 seconds. What is his power?
16 w
11.5 w
10 w
2,944 w
14
There are 6 types of levers.
True
False
15
A wheel and axle
none of the above
is just a pole
has a large side and a short side
breaks the laws of physics
16
When finding the efficiency of a compound machine, do you multiply or divide the efficiency of each simple machine?
both
divide
neither
multiply
17
What is a simple machine?
has one arm
uses only one movement
has low mechanical advantage
has several parts
18
Which is a third-class lever?
a nutcracker
a broom
a hammer
a wheelbarrow
19
A wheelbarrow is a ___ class lever.
4th
2nd
3rd
1st
20
Power is the rate at which energy is done.
True
False
21
What is the label for mechanical advantage?
joule
watt
newton
none
22
Which is NOT a true statement?
Efficiency is always less than 100%
Friction cannot be reduced.
Input force X input distance = output force X output distance
Input work is transformed into energy.
23
Output force/input force finds...
power
work
efficiency
mechical advantage
24
What machine works by changing the direction of a force?
a screwdriver
a can opener
a rake
a pulley
25
Changing the size of a force, distance a force acts, and direction of a force are ways machines
decrease power
make work easier
make work harder
increase power
26
The rate at which work is done is
motion
workd
power
efficiency
27
What is the equation for ideal MA for a wheel and axle?
R-axle - R-wheel
R-axle/R-wheel
R-wheel/R- axle
R-wheel - R-axle
28
How many types of simple machines are there?
7
3
6
5
29
efficiency = work output/work input x 100%
False
True
30
Force x distance determines what?
eficiency
power
work
force
31
A machine's efficiency is always less than 100%.
True
False
32
There are only 3 types of simple machines.
False
True
33
What is the equation for work?
w= fd
w = fp
w = s/d
W = f/d
34
If the input work to a machine is 100 J and the output work is 75 J, what is the efficiency of the machine?
125%
75%
175%
25%
35
Which lever always has a mechanical advantage greater than 1?
none of them
2nd
3rd
1st
36
What is the equation for ideal MA of a lever?
L-out/L-in
L-in - L-out
L-in x L-out
L-in /L-out
37
The transfer of energy that occurs when a force is applied over a distance is...
power
efficiency
fulcrum
work
38
What type of simple machine is a screw?
wheel and axle
lever
inclined plane
wedge
39
Which quantity increases when a frictionless ramp is used to lift an object?
input distance
input work
output work
input force
40
How do you find the efficiency of a compound machine?
find the median
add them together
find the mode
multiply all the efficiencies
41
What class of lever are your feet when you do a toe-up?
2
1
spongebob
3
42
If a chair is moved 5 meters in 2 seconds and required 20-N force, how much power was used to move it?
10 W
20 W
200 W
50 W
43
What simple machine has a grooved wheel with rope around it?
inclined plane
screw
wedge
pulley
44
Pulleys only change the direction of a force.
True
False
45
Which of the following is NOT a simple machine?
pulley
fulcrum
wedge
inclined plane
46
What is the machine's ratio of output work to input work?
work
power
efficiency
mechanical advantage
47
Which is a compound machine?
screw
block and tackle pulle
scissors
wheel and axle
48
A machine can have 100% efficiency.
False
True
49
Which is NOT a way a machine makes work easier?
the amount of energy
the direction of the force.
the size of teh force
the distance of the force
50
The point about which a lever rotates is called the pivot.
True
False
51
Which lever has the fulcrum between the input force and output force?
2nd class
3rd class
1st class
none of them
52
What is the equation for MA?
F-out x F-in
F-in + F-out
F-in/F-out
F-out/F-in
53
Which is NOT a lever in the body?
neck
arm
butt
leg
54
What is the equation for power?
work - time
time + distance
work/time
work x time
55
Which must be true if a machine's mechanical advantage is equal to 2?
Output work is greater than input work.
Direction of force is changed.
Output force is greater than input force.
Output force equals input force.
56
Work is
force minus distance
force over distance
distance times force
distance over force
57
Which distance do you measure to determine how much work was done on an object that has been moved?
distance in the direction of motion
vertical distance
all distance against gravity
horizontal distance
58
Which transfers both kinetic energy and potential energy to an object?
lowering it
rolling it
pushing it
lifting it
59
Work is measured in what?
Watts
joules
newtons
inches
60
A rake makes doing work easier by changing the
distance a force acts
size of the force
direction of the force
amount of work reqred
