[Problem M21—M25; F24—F28]

PROBLEM WORKER
quantum

F24. stand,
on which
the body lies
suspended
outside,
start
let down
acceleration α.
In the initial
moment
spring
not stretched.
Through
what time is it
the body will come off
from the stand?
Do what
maximum
length
will the spring stretch?
Body weight M,
spring stiffness κ.
N. I. Goldfarb

39

40

F25. If the potential of the anode of the photozement is higher than the potential of the cadada, then a current $I=10 \, a$ (so saturation) flows through the photozement. Otherwise, no current flows through the photozesment. Neglecting the internal resistance of the batteries, find the voltage across the photozems in the diagrams shown in figure 1 (resistance values ​​are indicated in kilums).

F26. Two horizontal half-planes, located at a height $h$ one above the other, smoothly transform into each other, as shown in figure 2. Along the upper half-plane at an angle $\alpha$ to the direction of descent, a small block moves at a speed $U$. How will it move along the lower half-plane? Assume that the block does not bounce, that is, it moves without leaving the surface of the descent. Neglect training.

F27. Water is poured into a hemispherical bell, lying tightly on the table, through the hole at the top (Fig. 3). When the water reaches the hole, it lifts the bell and begins to flow out. Find the weight of the bell if its radius is $R$ and the density of water is $\rho$.