Q1:
A positively charged point object can take two paths between
the points and shown in the diagram. The path shown in black is path I and
the path shown in red is path II. Path I is an arc of a circle, path II is a chord
of the same circle, and the dashed vertical line is the diameter of the same
circle. The horizontal dashed line is perpendicular to the dashed vertical
line. The point where the vertical and horizontal dashed lines intersect is the
fixed position of a negatively charged point object.
Which of the paths can the positively charged object
follow with zero work done on it by the negatively charged object at any time during the motion of the positively charged object?
Which of the paths can the positively charged object
follow with zero net work done on it by the negatively charged object?
Which of the paths can the positively charged object
follow where the power supplied by the negatively charged object is
constant?
For which of the paths does the net work done on
the positively charged object by the negatively charged object change if the
object moves from point to point instead of from point to point ?
For which of the paths is the net work done on the
negatively charged object by the positively charged object equal to zero?
Q3:
The surface of a lake is shown as altitude II in the
diagram. The vertical displacement between a hilltop at altitude I and altitude
II is 22 m.
The vertical displacement between altitude II and a mud bank at
altitude III is 18 m.
The vertical displacement between altitude III and the
lake bed at altitude IV is
27 m.
A boat with a mass of
110 kg slides down the hillside to the lake surface,
from altitude I to altitude II. The boat moves across the surface of the sea
and starts to sink, coming to rest on the mud bank.
What is the gravitational potential energy of the boat just
before it starts to sink? Take the lake bed at the base of the hill as the point of zero gravitational potential.
What is the gravitational potential energy of the boat just
before it starts to sink? Take the lake surface as the point of zero
gravitational potential.
What is the gravitational potential energy of a person with a mass of
75 kg who is on
the hilltop? Take a person in the boat just before it starts to sink as
the point of zero gravitational potential.
What is the gravitational potential energy of the boat when
it comes to rest? Take a person at the top of the hill as the point of zero
gravitational potential.
