mass, are 「 PASSAGE PROBLEMS
了 R/S BODY. Dancers experience
jjmps they make. Tor example
Speed7
sma-
jZOnta]
) case7?
he box
)n foT 7
ere no
an en-
)1S at-
了1S
and 1S
Ve Up-
glvVen
「graph
1 TV
planet,
when a dancef ]an
head by 過e neck
cause 負e head to $
9g.4% of atypical personsm
Janding after a Vertical Jump $
4.0 m/s to restinatime of 0.20 S.
4,57 What 1$ the magnitude Of the average force that her neck
exerts on her head during the ]anding? (3) ON; (b) 6O N; (c) 120 N:
must exceed the
jow down and come to Tes- The head is about
as8. Video analysis ot a 65-kg dancer
hows that her head decelerates from
hthe force her neck exerts on her head during
the ]anding, the force her head exerts On her neck 1S (3) the Sames:
(b) greater; (co) smaller: (d) greater during the first half ot the land-
uring the second halt of the ]anding.
4.,58 Compared Wit
9 and smaller d
4,59 While the dancer 1S in the air and holding a fixed bose
what is the magnitude of the force her neck exertS On her heady
(3 ON; (b) 6O N; (o]) 120 N; (0) 180 N.
4.60 The forces ona dancer can be measSsured directly When a
dancer performs aJump On a force plate that measSures the 10rfce
betWween her feet and the ground. A graph Of force verSus time
es a Vertical jump performed on aforce plate is Shown lt
es at 1S happening at 0.4 $? The dancer is (3) bendlng
0 1S acceleratling downward; (b) pushtung
er legs and is almost ready to leave the ground
(o in the air and at the to
have just touched the 一 her jump; (d) landing and her feel
Figure P4.60
