Question

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求圈起來的幾題

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For Thoughtand Diseussion

tneuish the Aristotelian and Galilean/Newtonian views ofihe
ball bounees ofrawall with the same speedithad beforeithit
Wall Has its momentum changed? Hasaforoe acted on the
2 Has aforee acted on the wall? Relate your answers to New
aws of motion
ten use the term "inertias to deseribe human sluggishness
5this usage related to the meaning ofFsinertiae in physics?
does aceiling fan continue to rotate even after you have
vitched it ofP?
Wek erashes into a Stalled cear A student trying to explain the
es ofthis event claims thar no forees are involved: the car
Tin the way”so itgot hit Commen
foot astronaut kicks a ball, hard, across aspace station

balls apparent weightlessness mean he astronauts toes

  

下avity on Jupiters moon Io is one-fifth that on

Would happen te your weight and to your mass if
nIo?

tis the direcetion of momentum oFamoving body? Does it

Fthe body:

plane aceelerates down the munway, you take your keys
r poeket and suspend them by a thread. Do they hang

force from the chairon you.
iir? Hnot, what forees are

 

fxerrisesaned Problems 85         $

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20。 Staring frorm rest and undergoing constan acceleratiom,a920-kg
ar covers 410 min $.15 8. Find the foree on the car

21      dropping dontest, a student encatses am 83-g cgg in
large Styrofoam block. fs         g emn'texceed 2.0N
and 計the bloek hits the g               pow mueh must
the Styror   jompress on impaet) Note: The aceelei
assoeialed with stOppi
gravity while the Styrofe
the ground.

22. Inatront-end collision, a 1400-kg car with shockzabsorbing bump:
ems can withstand amaximum force of 75kN before damage Gccurs:

 

Hthe maximum speed foranondamaging collision is 9.0 kmzh, by

Bow much must he bumper be able to move relative to the car?
section 4.4 The Force ofGravity

23。 Show that the units of aceeleration can be written as N/kg- Why
doesitmake sense to give gas 9.8 N/kg when talking about imass
and weight?

24. Your spaceship crashes on one of the Sun's planets, Fortunately          上

the ship's scales are intact and show that your weightis 680 N.H

your mass is 58 kg, where are you? (imr: Consult AppendixEE)

Your friend can barely lift a 35-kg concrete block on E:

massive ablock could she lift on the Moon?

26 Acereal box says "net weight 350 grams” Whats the actual
Weight ta in SLunits and (b) in ounees?

27. Youre asafety engineerforabridge spanning the U,S-Canadian
border. U.S. speeifications permit a maximum load of 10 tons
What load iimit should you speeify on the Canadian side. where
welght is given in kilograms?

28.。 The gravitational acceleration atthe lntermational Space Stations
altitude is about 91凶 oFits surface value. Whats the weightofa
64-kg astronaut atthis altitude?

ection 4.5 Using Newton's SecondLaw

 A 50-kg parachutist deseends atasteady 40 km/h. What foree
does air exert on the parachute?

30, A 960-kg motorboat accelerates away from adock at2.1 m/s
Its propellerprovides a3.9-kN thrust force. What drag force does
the water exert on the boat?

An elevator aceelerates downward at2.4 ms. What force does
the elevator's floor exertona52-kg passengery

32. At 560 metric tons, the Airbus A-380 is the World's largest air-

liner Whats the upward force on an A-380 when the plane is
(am flying at constant altitude and (b) aceelerating upward at
15m/s2?

33. Yourre an engineer working on Ares 1 NASAs replacement tor
the space Shuttles. Performance speces call for afirst-stage TOcket
Gapable ofaccelerating atotal mass 0f 600 Me vertically ftom
Testt0 7700 km in 1.7 min. Youre asked to determine tbe re-
quired engine thrust (force) and the foree exerted ona79-kg as-
tronaut during Tiftoff. What do you Teport?

34. You step into an elevatorand itacceleratesto adownward speed

gfF8.8 mAS in 2.4 5 Quantitatively compare your apparent weight

during thistime with youracetual weight,

44.6 NewtonsThirdLaw
ional foree does 3 5600-kg elephant exer

 

 

 

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63.      she jumps ofta140-emhi過台
人     rdheras she falls?

4 FOFCe ad Motion     蛻.
生                           ym, Ff 1t5 spTIn喲

ing 48
retch a sprIn
What foree is neceSsary to Stretch a 8PT  4

constantis 270 N/m7
38. A 35-N force is applied toa
三 260 N/m. How much does the 和 生
39. Aspring with spring constant 大 守  只的
6.7-kg fish. How fr does the sprInE Stretch:

~    ant
ith spfing cos

h7

used to weigh a

Problems                                  9           ie
40. A 1.25-kg object is moving 呈 the direetion at 1
3.31 slater is moving at27.8 m/s at 32.07 to the共說一

          pthis time-
magnitude and direction ofthe force applied durlng 由
41. An airplane encounters sudden turbulence 1 70% of
farily Jighter. IF your apparent weight seems to  說     全
your normal weight, what are the magnitude and direction o
Plane's acceleration?                              呈
42. A 70-kg tree surgeonridesa “cherry picker” 1ift to reach the up
per branches ofa tree. What force does the lift exert On the sur-
geon when its (a) atrest; (b) moving upward at a steady 2.3 m/S;
(e) moving downward at a steady 2.3 m/S; (d) accelerating up-
ward at 1.3 m/s-; (e) accelerating downward at 1.3 m/s2?

43. A daneer executes a vertical jump during which the floor pushes
up on his feet with a foree 44% greater than his weight. What s
his upward accejeration?

44. Fnd expressions for the force needed to bring an object of mass
中 Test to speedp(a) in time Aand (b) over distance A志
9  、  elevator mmoves upward at 5.9 m/s. Whats its minimum stop-
誠   Ping time 導向e passengers are to remain on the floor?
  AA 2.50-kg object IS moving 引ong the x-axis at 1.60 m/Ss. As
 passes 負e origin, two forces 吳:    台        人章
           說間                 1and /2 are applied, both
號負e y-direction (plus     i            答@
P us Or minus). The forces are applied ff
3.00 5s, after which the object is atx 三 4.80        pplied for
五二15.07 N, whats 及?         還IT

                                               

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