Lesson - Screws and Frictions

Why do we use inclined planes ?

• Ramps are nicer to use

• We can reduce the amount of required work

• Its funner

• To increase frictional force

What is friction

• A resistant force which resists movement

• A resistant force caused by the sliding of 2 surfaces against one another

• A sliding force, which reduces the velocity of an object

• A force, which limits the maximum speed of a flying object

Which of these factors affects the amount of friction experienced?

• The smoothness of the object/surface interface

• The smoothness of the object with the air

• The amount of force applied on the object

Which produces the most frictional force

• A single screw in a block of wood

• A nail in wood

• two phone books interlaced together

Which of these systems uses screws ?

• drills (Hand tools)

• Tap

• Screws

• Nails

Which of these physical concepts are used for screws?

• Electric fields

• Inclined Planes

• Friction

• Pulleys

How does a kitchen mincer use screws ?

• Shred meat (Cutting Blade)

• As an auger (move the meat)

• Capture and hold the meat

• Reduce the amount of torque (rotational force) required

How are screws used in Combine Harvesters? [Multiple Answers]

• Cut the Wheat(crop)

• Transport the grains

• Unloading the grain

• Sift the grain

Why do we use corkscrews to remove cork?

• To increase the amount of grip on the cork

• It is fun to use

• Allows for air to escape the bottle

• Because we are removing a cork

Which of these systems have friction (not air - resistance)

• A plane flying in the air

• Car driving on the road

• Block of ice sliding on glass

• Human walking on the street