118
Aptitude Test Problems in Physicsdicular to two intersecting straight lines AC and
BC, which is impossible. Consequently, in the
moving reference frame, the velocity of point C
is zero, while in the initial system (fixed to the
ground), the velocity of point C is equal to the
velocity of points A and B.
If point C lay on the straight line AB (in the
reference frame fixed to the sheet of plywood) and
its velocity differed from zero, after a certain small
time interval either the distance AC or the dis-
tance BC would increase, which is impossible.
Therefore, in the motion of the sheet of ply-
wood under consideration, the velocities of all
the points are identical.
1.13. Let a car get in a small gap between two
other cars. It is parked relative to the pavement
as shown in Fig. 129. Is it easier for the car to be
/7AFig. 129 Fig. 130
driven out of the gap by forward or backward mo-
tion? Since only the front wheels can be turned,
the centre 0 of the circle along which the car is
driven out for any manoeuvre (forward or back-
ward) always lies on the straight line passing
through the centres of the rear wheels of the car.
Consequently, the car being driven out is more
likely to touch the hind car 'during backward mo-
tion than the front car during forward motion (the
centre of the corresponding circle is shifted back-