SunÕs gravitational pull on the Earth is much larger than the MoonÕs. Yet, the MoonÕs gravitational pull is
mainly responsible for the tides.
Can you explain this?
Sun is directly below us at midnight, in line with the EarthÕs center. Are we then heavier at midnight, due to
the SunÕs gravitational force on us, than we are at noon? Make an estimate of the difference in
weight (if any).
the system shown below. The
coefficient of kinetic friction between block A (with weight Wa) and
the table top is mk.
(a) Calculate the weight Wb of the hanging block required if
this block is to descend at constant speed once it has been set into
motion. (b) Suppose the
coefficient of static friction is ms = 0.4 and the mass of A
is 30 kg and the mass of B is 2 kg.
What is the force of friction on mass A now (assuming an initial
condition of no motion)? How will
the system move as time increases?
density of a certain planet varies with radial distance as r(r) = r0(1-ar/R0) where R0 is the radius of
the planet, r0 is its central density,
and a is a dimensionless constant. (a) What is the total mass of the
planet? (b) Calculate the weight
of a one-kilogram mass located on the surface of the planet.
moves faster in its orbit around the sun in December than in June. Is it closer to the Sun in June or in
December? Does this effect the
the drawing below. In terms
of M1, M2 and g, find the acceleration of each block in
the system. Assume there is no
friction anywhere in the system.
Check your solution with limiting cases.