課程名稱︰普通物理學乙
課程性質︰必修或選修可抵通識
課程教師︰洪在明
開課系所︰物治系
考試時間︰6/23/2006 14:20~17:20
是否需發放獎勵金：是
試題 :
- Final (每題15分，總分120分，滿分100分) -
１.(Problem 6.8) Suppose the ski patrol lowers a rescue sled and victim,
having a total mass of 80.0kg,down a 60.0° slope at constant speed.
The coefficient of friction between the sled and the snow is 0.100.
a)How much work is done by friction as the sled moves 30.0m along the hill?
b)How moch work is done by the rope on the sled in this distance?
c)What is the work done by gravity on the sled?
２.(Problem 7.58) A highly motivated Indiana Jones swings on a vine to rescue
a heroine,scooping her into his arm at the bottom of his swing and taking
her up to temporary safety on a ledge. Indiana's mass is 70.0kg,the
heroine's is 50.0kg,and ledge from which he starts is 8.00m above the low
point of his swing.
a)What is his velocity just before he scoops her up,assuming he starts from
rest?
b)What is their velocity just after scooping her up?
c)How much kinetic energy is lost in their collision?
d)What is the highest ledge they can swing to?
３.(Problem 7.68) Squids have been reported to jump from the ocean and travel
30.0meter(measured horizontally) before reentering the water.
a)Calculate the initial speed of the squid if it leaves the water at an
angle of20.0° ,assuming negligible lift from the air and negligible air
resistance.
b)The squid propels itself by squirting water.What fraction of its mass
would it have eject in order to achieve the speed found in the previous
part? The water is eject at 12.0m/s; gravity and friction are neglected.
c)What is unreasonable about the results?
４.(Problem 8.23) A large centrifuge is used to expose aspiring astronaunt to
accelerations similar to those experienced in rocket launches and
atmospheric reentries.
a)At what angular velocity is the centripetal acceleration 10 gs if the
rider is 20.0m from the center of rotation?
b)The rider's cage hangs on pivot at the end of the arm,allowing it to swing
outward during rotation. At what angle below the horizontal will cage hang
when the centripetal acceleration is 10 gs?
５.(Problem 8.41) Rider in an amusing park ride shaped like a Viking ship
(海盜船) hung from a large pivot are rotated back and forth like a rigid
pendulum. Sometime near the middle of ride, the ship is momentarily
motionless at the top of its circular arc. The ship then swing down under
the influence of gravity.
a)Assuming negligible friction,find the speed of the riders at the bottom
of its arc,given the system's center of mass travels in an arc having a
radius of 15.0m and the riders are near the center of mass.
b)What is the centripetal acceleration at the bottom of the arc?
c)Find the force exerted by the ride on a 60kg rider and compare it to her
weight.
６.(Problem 9.24) While exercising in fitness center,a man lies face down on a
bench and lifts a weight with one lower leg by contacting the muscles in the
back of the upper leg.
a)Find the angular acceleration produced given the mass lifted is 10.0kg at
a distance of 30.0cm from the knee joint,the moment of inertia of lower
leg is 0.900 kg˙m^2 ,the muscle force is 1500N,and its effective
perpendicular lever arm is 3.00cm.
b)How much work is done if the leg rotates through an angle of 30.0° with
a constant force exerted by the muscle?
７.(Problem 9.36)
a)Calculate the angular momentum of an ice skater spinning at 6.00rev/s
given his moment of inertia is 0.500kg˙m^2 .
b)He reduces his rate of spin(his angular velocity) by extending his arms
and increasing his moment of inertia.Find the value of his moment of
inertia if his angular velocity drops to 1.20rev/s.
c)Suppose instead he keeps his arms in and allows friction with the ice to
slow him to 3.00rev/s.What average torque was exerted if this takes 15
seconds?
８.(Problem 10.44) A rock with a mass of 540g in air is found to have an
apparent mass(指在水中量得的質量) of 340g when submerged in water.
a)What mass of water is displaced?
b)What is the volume of the rock?
c)What is its average density?
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