20 Aptitude Test Problems in Physics
when the constant force starts acting.
1.34. A person carrying a spring balance
and a stopwatch is in a closed carriage stand-
ing on a horizontal segment of the railway.
When the carriage starts moving, the per-
son sitting with his face in the direction of
motion (along the rails) and fixing a load of
mass m to the spring balance watches the
direction of the deflection of the load andthe readings of the balance, marking the
instants of time when the readings change
with the help of the stopwatch.
When the carriage starts moving and the
load is deflected during the first time inter-
val t 1 = 4 s 'towards the observer, the bal-
ance indicates a weight 1.25mg. During
the next time interval t 2 = 3 s, the load
hangs in the vertical position, and
the balance indicates a weight mg. Then the
load is deflected to the left (across the car-
riage), and during an interval t 3 =25.12 s,
the balance again indicates a weight
1.25mg. Finally, during the last time inter-val t (^4) = 4 s, the load is deflected from the
observer, the reading of the balance
remaining the same.
Determine the position of the carriage rel-
ative to its initial position and its veloci-
ty by this instant of time, assuming that
the observer suppresses by his hand the os-
cillations resulting from a change in the
direction of deflection and in the readings
of the balance.
1.35. Two identical weightless rods are
hinged to each other and to a horizontal