M. 282. By means of a compass measure the magnetic induction of a bar magnet as a function of the distance r measured from the centre of the magnet. The measurements should be carried out along two lines:
a) the longitudinal axis of the bar magnet;
b) perpendicularly to the longitudinal axis.
You may use that the horizontal component of the magnetic induction of the Earth is 2.10-5 T.
P. 4016. The axle of a pulley of mass m=1 kg is attached to the end of a spring of spring constant D=200 N/m whose other end is fixed to the ceiling. A rope of negligible mass is placed to the pulley such that its left end is fixed to the ground and its right end is hanging freely from the pulley. At one moment we begin to pull the endpoint A at the right end of the rope by a constant vertical force of F=15 N. Friction can be neglected between the rope and the pulley.
a) What is the initial elongation of the spring?
b) Find the greatest elongation of the spring.
c) Find the maximum displacement of point A.