Exercises and problems in Physics
New experimental problem:
How many cubic centimetres of gas are released during the dissolution
of a single sparkling tablet?
FGy. 3079. In order to crack nuts bare-fisted, one usually
takes two nuts into one's hand at the same time. Why is it easier to
crack a nut with this method?
FGy. 3080. In the house of a person who is weak of hearing, a
light bulb is also lit when somebody rings the door-bell. The ring
can be operated both from the garden gate and from the door of the
house. Draw such a circuit.
FGy. 3081. The speed of a 100-metre-wide river is 2 m/s everywhere.
A boat that can travel at a constant speed of 1 m/s in standing water
sets off from one bank. How far is the nearest point that the boat can
reach on the opposite bank?
FGy. 3082. In the figure ammeter I reads a current of 10 mA,
while the voltmeter reads a p.d. of 3 V. What does ammeter II read?
The ammeters are identical, the internal resistance of the battery is
FF. 3083. The height of the cabin of a spacecraft is 3 metres.
The air in the cabin is in normal state. What is difference between the
pressure at the floor and at the ceiling of the cabin
a) before taking off, in the vertical position of the cabin?
b) after taking off, when the spacecraft rises with an acceleration
of 40 m/s2?
c) when the spacecraft orbits the Earth?
FF. 3084. An insect sets off upwards from the shaft
of the minute hand of a church-clock exactly at 12 o'clock. Moving
uniformly along the hand, it reaches the end of the hand in a quarter of
an hour. When was it at the highest position?
FF. 3085. A prism of height h, width h/2 and mass
M and with a homogeneous mass distribution is placed onto a horizontal
plane. One end of a thread running in a pulley is fastened to the bottom of
the prism, a body of mass m is hung from the other end and the system
is left alone. Friction is negligible everywhere. At what ratio m/M
is the prism tilted?
FF. 3086. A small body of mass m and speed
slides up onto a slope of mass M standing on a horizontal surface.
Friction is negligible everywhere, the bottom of the slope is tangent to
the horizontal plane. What is the maximum height the small body can reach
on the slope?
FF. 3087. Large rain drops grow by capturing small rain drops that
collide with them during their fall. Give an estimate of the increase of
mass in 10 seconds of a drop with a diameter of 3 mm, the speed of which
grows uniformly from 5 m/s to 7 m/s. The drop in question hits droplets
with a diameter of floating in the
air. The spatial distribution of the droplets is uniform, there are 200
of them in average in a cubic centimetre.
New advanced problem:
FN. 3088. A certain helicopter can hover when the mechanical power
output of its engine is P. A second helicopter is an exact copy of
the first one, but reduced to 1/2 (its linear dimensions are
half as large). What mechanical power output is needed to make this second