DYNAMICS ON RIGID BODIES
PROBLEM SET
1-2. On a certain stretch of track, trains run at 60 mph (96.56 kph). How far back of
a stopped
train should be a warning torpedo be placed to signal an oncoming train? Assume
that the
brakes are applied at once and retard the train at the uniform rate of 2 ft/sec2 (0.61
m/s2). Give the answer in SI and in English unit.
3-4. A stone is thrown vertically upward and return to earth in 10 sec. What was its
initial
velocity and how high did it go? Give the answer in SI and in English unit.
5-6. A ball is dropped from the top of a tower 80 ft (24.38 m) high at the same
instant that a
second ball is thrown upward from the ground with an initial velocity of 40 ft/sec
(12.19
m/s). When and where do they pass, and with what relative velocity? Give the
answer in SI and in English unit.
7-8. A stone is dropped down a well and 5 sec later, the sounds of the splash is
heard. If the
velocity of sound is 1120 ft/sec (341.376 m/s), what is the depth of the well? Give
the answer in SI and in English unit.
9-10. Repeat problem 7-8 if the sound of the splash is heard after 4 sec. Give the
answer in SI and in English unit.
11-12. A stone is dropped from a captive balloon at an elevation of 1000 ft (304.8
m). Two
seconds later another stone is thrown vertically upward from the ground with a
velocity
of 248 ft/s (75.6 m/s). If g = 32 ft/s2 (9.75 m/s2), when and where the stones pass
each
other? Give the answer in SI and in English unit.
13-14.. A stone is thrown vertically upward from the ground with a velocity of 48.3
ft per sec
(14.72 m per sec). One second later another stone is thrown vertically upward with
a
velocity of 96.6 ft per sec (29.44 m per sec). How far above the ground will the
stones be
at the same level? Give the answer in SI and in English unit.
15-16. A ball is shot vertically into the air at a velocity of 193.2 ft per sec (58.9 m
per sec). After
4 sec, another ball is shot vertically into the air. What initial velocity must the
second ball
