Download Raising and Lowering

Raising and Lowering
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A box is lowered at constant velocity. Does the acceleration
depend on the velocity? What is the net force on the box? Draw
a force diagram for the box.
Acceleration = rate of change in
velocity = 0 for any size constant
velocity (5 – 5 = 0, 10 – 10 = 0, etc.)
The net force = mass x acceleration = 0
velocity
FT
Acceleration = 0
mg
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A box is raised at constant velocity. Is the acceleration +, -, or 0?
What is the net force on the box? Draw a force diagram for the
box.
Acceleration = rate of change in
velocity = 0 since velocity does not
change
The net force = mass x acceleration = 0
velocity
FT
Acceleration = 0
mg
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A box is lowered with uniformly increasing speed and more
negative velocity. Is the acceleration +, -, or 0? Is the net force on
the box, up, down or zero? Draw a force diagram for the box.
Acceleration is (-) since the velocity is
becoming more negative
The net force = mass x acceleration
which is downwards since acceleration is
downwards.
FT
acceleration
velocity
mg
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A box is raised with uniformly increasing speed and more
positive velocity. Does the acceleration depend on the velocity?
Is the net force on the box, up, down or zero? Draw a force
diagram for the box.
Acceleration is (+) since the velocity is
becoming more positive
The net force = mass x acceleration
which is upwards since acceleration is
upwards.
FT
acceleration
velocity
mg
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A box is lowered with uniformly decreasing speed and less
negative velocity. Draw a motion diagram for the box. Is the net
force on the box, up, down or zero? Draw a force diagram for the
box.
Acceleration is positive, e.g. velocity might
change from -10 to -5, an increase of +5.
The net force = mass x acceleration
which is upwards since acceleration is
upwards.
acceleration
It takes a net upward force to
slow the descent of the box.
velocity
FT
mg
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A box is raised with uniformly decreasing speed and less positive
velocity. Draw a motion diagram for the box. Is the net force on
the box, up, down or zero? Draw a force diagram for the box.
Acceleration is negative, e.g. velocity might
change from +10 to +5, a change of -5.
The net force = mass x acceleration
which is downwards since acceleration is
downwards.
FT
acceleration
mg
velocity
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