Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

Solutions 157

we can use the energy and momentum conservation

laws:

Mv2 mu2

2 2 =

mgh, My = mu.

Since at the moment of maximum ascent hmax

of the washer along the right wedge, the velocities

of the washer and the wedge will be equal, the

momentum conservation law can be written in the

form

mu =-- (M m) V,

where V is the total velocity of the washer and the

right wedge. Let us also use the energy conserva-

tion law:

mu 2 m

2 --

2

V 2 - 1 - mghmax•

The joint solution of the last two equations leads

to the expression for the maximum height hmax

of the ascent of the washer along the right wedge:

M 2

hmax h (^) ± no •
1.55. The block will touch the wall until the wash-
er comes to the lowest position. By this instant of
Fig. 161
time, the washer has acquired the velocity v which
can be determined from the energy conservation
law: v (^2) = 2gr. During the subsequent motion of
the system, the washer will "climb' the right-hand
side of the block, accelerating it all the time in
the rightward direction (Fig. 161) until the veloc-