An object with a constant net force
will have a constant speed.
A refrigerator is pushed across a floor, to the east, at a
constant speed. Draw a vector to represent the direction of the
net force acting on the refrigerator. If the net force is zero, state
that explicitly. Explain your answer.
A refrigerator is pushed across the floor, to the east, with a
constant net force, also directed to the east. Which of the following
best describes the motion of the refrigerator? Explain your
a. It slows down as it moves across the floor.
b. It travels at a constant speed across the floor.
c. It speeds up as it moves across the floor.
d. Can't be answered without more information about the
A refrigerator is pushed across the floor, to the east, such that
it speeds up by 1 cm/s each second as it moves. Which of the
following best describes the net force acting on the refrigerator?
Explain your choice.
a. It is increasing.
b. It is constant.
c. It is decreasing.
d..Can't be answered without more information about the
Students who suffer from this misconception believe that a
constant net force is needed to propel an object at a contant speed.
This misconception could arise from the everyday experience of
pushing an object across a surface (at a roughly constant speed)
which has friction, and not being aware that the friction is acting
on the object with an equal amount of force in the opposite
Related misconceptions/student difficulties that may arise in the
force accelerates a body, until the body uses up all the power of
The net force must be
in the direction of motion, so objects will travel along a line in
Faster moving objects
have a larger force acting on them.
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