問題一覧
1
machines that are built by putting together two or more simple machines are call
compound machines
2
you exert an input force on a hammer. the hammer exerts a(n) force on the nail.
output
3
the amount by which a machine multiplies an input force is called the .
mechanical advantage
4
a dressmaker is cutting fabric. She applies 18 J of work to the scissors. The scissors apply 15J of work to the fabric as it cuts. What is the efficiency of the scissors?
83%
5
which one of the following is NOT an example of work being done?
the moon orbiting earth
6
find the force needed to lift a 2000N rock, using a jack with a mechanical advantage of 10
200N
7
a worker applies a force of 20N to pry open a window that has a resistance force of 500N. what is the mechanical advantage of the crowbar?
25
8
joe is using a crowbar to remove a tree stump. He applies 2066 J of work to the crowbar. The output work of the crowbar is 1240 J. what is the efficiency of the crowbar?
60%
9
a winding mountain road is an example of a(n)___.
inclined plane
10
the force exerted by your foot on the pedal to ride your bike is an example of .
input force
11
efficiency
output work and divide; input work
12
ideal mechanical advantage
radius of a wheel and divide; radius of axle
13
mechanical advantage
out put force and divide; input force
14
power
work and divide; time
15
work
force and times; distance
16
ratio of ouput force to input force
mechanical advantage
17
force you apply to a simple machine
input
18
device made it more than one simple machine
output focre
19
knife
wedge
20
leaf rake
lever