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simple machines make work easier. most simple machines reduce the amount of effort force needed to move an object. this cart has a set of wheels. the wheels are actually simple machines: the wheel and axle. how can we change these wheels to decrease the amount of effort force needed to move the wagon?
a) use a larger wheel and axle. b) make the radius of the axle larger in diameter.
c) make the radius of the wheel larger in diameter.
d) make the radius of the wheel smaller in diameter.
we can classify both the shovel and the garden trowel as compound machines. this is because each garden tool contains two simple machines,
a) a lever and a wedge.
b) a blade and a handle.
c) a lever and a pulley.
d) an inclined plane and a wedge.
a block-and-tackle is a machine that uses pulleys to lift heavy items. a person pulls on one end of a rope with an effort force. the other end is attached to the item, or load. the table shows the results of testing several block-and-tackle designs to pull the load one meter off the ground.
which design has the greatest efficiency?
a) block-and-tackle a
b) block-and-tackle b
c) block-and-tackle c
d) block-and-tackle d