UNL2207 - The Nature of Natural Law: Tutorial 5
Conservation Laws
1) A roller coaster is pulled to the top of a chute and allowed to roll down (ignore friction),
arriving at the bottom at a certain speed.
height
To get a bigger thrill and arrive at the bottom with twice this speed, the chute would need to
be
a) twice
b) three times
c) four times
d) five times
e) six times
as high.
2)
Suppose an open railroad car is rolling without friction in a vertically- falling
downpour and an appreciable amount of rain falls into the car and accumulates there.
Consider the effect of the accumulating rain on the speed, momentum and kinetic energy of
the car. Each of these will respectively
a) increase
3)
b) decrease
c) not change
Explore the physics simulation http://www.walter-fendt.de/ph14e/ncradle.htm
Write down the equations expressing conservation of momentum and conservation of energy
for these two systems respectively and use your equations to discuss the observed motions.
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4)
A rubber bullet and an aluminum bullet both have the same size, speed and mass. They
are fired at a block of wood. Which is most likely to knock the block over? Which is most likely
to damage the block?
5)
A ball attached to a string is rotating in a large horizontal circle. The string is then pulled
in so that the ball now rotates in a smaller circle. When the ball is spinning around the smaller
circle, it’s speed is
a) greater
b) less
c) unchanged
6)
Pull a pendulum to one side and let it go; as it swings back and forth, the pendulum is
conserving
a) linear and angular momentum
b) only angular momentum
c) only linear momentum
d) neither linear nor angular momentum
7)
A geosynchronous satellite is one that stays above the same point on the equator of
the Earth. Such satellites are used for such purposes as TV transmission, for weather
forecasting, and as communications relays. Determine a) the height above the Earth’s surface
such a satellite must orbit and b) such a satellite’s speed. c) With what velocity (speed and
direction) would the satellite have to be launched if it is to escape from the earth’s
gravitational field altogether?
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