When you use a screwdriver, you
apply an input force to turn the handle, or wheel
. Because the wheel is larger than the shaft, or axle, the axle rotates and exerts a large output force. The wheel and axle increases your force, but you must exert your force over a long distance.
What is the mechanical advantage of a screwdriver?
In this case, the mechanical advantage offered by the screwdriver is
the ratio of the handle radius to half the blade width (or the handle diameter to the blade width)
, or r
handle
/r
blade
. The overall actual mechanical advantage, however, can depend on the dimensions of what you are turning with the screwdriver.
How does a screw change the direction of force?
Screws move objects to a higher elevation (or greater depth)
by increasing the force applied
.
How do simple machines change the force that is applied to them?
load? Simple machines function to change the magnitude of a force or the direction of a force. They use
mechanical advantage
, which is also known as leverage, to multiply the amount of force exerted on a load.
Does a screw make work easier by changing the direction of the force?
Contrary to popular belief, machines do not increase the amount of work that is done. They just change how the work is done.
Machines make work easier by increasing the amount of force that is applied
, increasing the distance over which the force is applied, or changing the direction in which the force is applied.
Which screw would require the most force to turn?
In the
screw on the right
, the threads of the inclined plane are closer together. This screw has a greater mechanical advantage and is easier to turn than the screw on the left, so it takes less force to penetrate the wood with the right screw.
What two simple machines make up a screw?
So modern screws with their screwdrivers are a combination of two simple machines –
the inclined plane and the lever
.
What is used to change the direction of force?
A fixed pulley
is a device that is used to change the direction of the force you pull to move an object up.
Can a simple machine change the direction of force?
Simple Machines are tools that make work (using a force to move an object) easier. Simple machines
can change the direction of a force
or the amount of force needed. A simple machine has few or no moving parts and only one force is applied to it.
What are two examples of machines that change the direction of force?
Some machines change the direction of the force applied by the user. They may or may not also change the strength of the force or the distance over which the force is applied. Two examples of machines that work this way are
the claw ends of hammers and flagpole pulleys
.
What material was the first Archimedes screw used to move?
Originally, Archimedes screws were composed of
wood
, but gradually wood was replaced by metal.
Which example of levers would require the least amount of force to move the box?
Think back to the example of the
ramp
and the moving truck. The ramp reduced the amount of force needed to lift the box by moving it over a greater distance. The longer an inclined plane, the less force is required to move an object upward.
Does a nail or screw use less force?
Shear strength is the amount of force a fastener can handle from the sides. A nail,
has more elasticity than a screw
. This means as forces are pushed against the sides of a nail, the nail can bend slightly to accommodate these pressures. A screw conversely has very little shear strength.
Why are screws so strong?
Threaded fasteners are
strongest in tension (being pulled apart)
not in shear (slide apart). As a result, they prevent parts from sliding relative to each other by their clamp force not from the body of the fastener acting like a pin.
How do you force a screw in?
Place a
flat piece of rubber band over the screw head then firmly stick the driver tip in the head
, through the rubber, and turn. The rubber will create traction and help the screwdriver to catch the opening in the head.
Which pulley system would require the least amount of effort to lift the weight?
A movable pulley
needs less effort to lift a load BUT requires it to be pulled a longer distance.
