Lesson 01 to 20 Review

8/10/2019 Lesson 01 to 20 Review

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Physics 30 Lessons 1 to 20 Review

Kinematics

1. Emily takes a trip, driving with a constant velocity of 89.5 km/h to the north except for

a 22. min rest stop. !f Emily"s average velocity is ##.8 km/h to the north, how long

does the trip take$ %2.82 h&

2. 'o ()alify for the finals in a racing event, a race car m)st achieve an average speed of

25 km/h on a track with a total length of 1* m. !f a partic)lar car covers the first

half of the track at an average speed of 2+ km/h, what minim)m average speed m)st it

have in the second half of the event to ()alify$ %28 km/h&

+. - tortoise can r)n with a speed of 1. cm/s, and a hare can r)n exactly 2 times as

fast. !n a race, they oth start at the same time, )t the hare stops to rest for 2. min.

'he tortoise wins y 2. cm. %a& ow long does the race take$ %& 0hat is the length

of the race$

%12* s, 12.* m&

. )nner - is initially *. km west of a flagpole and is r)nning with a constant velocity

of 9. km/h d)e east. )nner 3 is initially 5. km east of the flagpole and is r)nning

with a constant velocity of 8. km/h d)e west. ow far are the r)nners from the

flagpole when their paths cross$ %.2 km west of flagpole&

5. - worker drops a wrench from the top of a tower 8. m tall. 0ith what velocity does

the wrench strike the gro)nd$ %4+9.* m/s&

*. - physics st)dent throws a softall straight )p into the air. 'he all was in the air for a

total of +.5* s efore it was ca)ght at its original position. %a& 0hat was the initial

velocity of the all$ %& ow high did it rise$ %1#.5 m/s, 15.5 m&

#. - small sandag is dropped from rest from a hovering hot4air alloon. -fter 2. s, what

is the velocity of the sandag and how far elow the hot4air alloon is the sand ag$ %4

2. x 11m/s, 42. x 11m&

8. - all thrown vertically )pward is ca)ght y the thrower after 5. s. %a& 6ind the initial

velocity of the all. %& 6ind the maxim)m height it reaches. %25 m/s, +1 m&

9. - peregrine falcon dives at a pigeon. 'he falcon starts downward from rest with free4

fall acceleration. !f the pigeon is #*. m elow the initial position of the falcon, how

long does it take the falcon to reach the pigeon$ -ss)me that the pigeon remains atrest.

%+.9 s&

1. - all is thrown )pward from the gro)nd with an initial speed of 25 m/s7 at the same

instant, a all is dropped from rest from a )ilding 15 m high. -fter how long will the

alls e at the same height$ %.* s&

11. - rocket moves )pward, starting from rest with an acceleration of 29. m/s2for . s.

!t r)ns o)t of f)el at the end of the . s )t does not stop. ow high does it rise aove

the gro)nd$ %95 m&

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12. - all is thrown vertically )pward with a speed of 25. m/s from a height of 2. m.

a. ow high does the all rise$ %+1.9 m&

. ow long does it take to reach its highest point$ %2.55 s&

c. ow long does the all take to hit the gro)nd after it reaches its highest point$

%2.*+ s&

d. 0hat is the all"s velocity when it ret)rns to the level from which it started$

%425. m/s&

1+. - mo)ntain climer stands at the top of a 5. m cliff hanging over a calm pool ofwater. 'he climer throws two stones vertically 1. s apart and oserves that they ca)se

a single splash when they hit the water. 'he first stone has an initial velocity of 2.

m/s.

a. ow long after release of the first stone will the two stones hit the water$ %+. s&

. 0hat is the initial velocity of the second stone when it is thrown$ %49.2 m/s&

c. 0hat will the velocity of each stone e at the instant oth stones hit the water$

%4+1. m/s, 4++ m/s&

1. - model rocket is la)nched straight )pward with an initial speed of 5. m/s. !t

accelerates with a constant )pward acceleration of 2. m/s2)ntil its engines stop at an

altit)de of 15 m.a. 0hat is the maxim)m height reached y the rocket$ %+1 m&

. 0hen does the rocket reach maxim)m height$ %8.5 s&

c. ow long is the rocket in the air$ %1*. s&

15. 'wo cars are travelling along a straight line in the same direction, the lead car at 25 m/s

and the other car at +5 m/s. -t the moment the cars are 5 m apart, the lead driver

applies the rakes, ca)sing the car to have an acceleration of 42. m/s 2.

a. ow long does it take for the lead car to stop$ %12 s&

. -ss)me that the driver of the chasing car applies the rakes at the same time as

the driver of the lead car. 0hat m)st the chasing car"s minim)m negative

acceleration e to avoid hitting the lead car$ %4+.1 m/s 2&

c. ow long does it take the chasing car to stop$ %11 s&

1*. ne swimmer in a relay race has a .5 s lead and is swimming at a constant speed of

. m/s. 'he swimmer has 5. m to swim efore reaching the end of the pool. -

second swimmer moves in the same direction as the leader. 0hat constant speed m)st

the second swimmer have in order to catch )p to the leader at the end of the pool$

%.1# m/s&

Vectors

1. - girl delivering newspapers covers her ro)te y travelling three locks west, fo)r

locks north, then six locks east. %a& 0hat is her res)ltant displacement$ %& 0hat is

the total distance she travels$ %5 locks 5o: of E, 1+ locks&

2. - s)marine dives 11. m at an angle of 1. elow the hori;ontal. 0hat are the

hori;ontal and vertical components of the s)marine"s displacement$ %18 m, 419 m&

+. - ()arterack takes the all from the line of scrimmage, r)ns ackward for 1. yards,

then r)ns sideways parallel to the line of scrimmage for 15. yards. -t this point, he

throws a 5.4yard forward pass straight down the field. 0hat is the magnit)de of the

footall"s res)ltant displacement$ %2.# yards&

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. - golfer takes two p)tts to sink his all in the hole once he is on the green. 'he first

p)tt displaces the all *. m east, and the second p)tt displaces it 5. m so)th. 0hat

displacement wo)ld p)t the all in the hole in one p)tt$ %8.# m 2.o< of E&

5. - kayaker paddles )pstream in a river at +.5 m/s relative to the water. servers on

shore note that he is moving at only 1.# m/s )pstream. =etermine the velocity of the

c)rrent in the river. %41.8 m/s&

*. - >et4ski speeds across a river at 11 m/s relative to the water. 'he >et ski"s heading isd)e so)th. 'he river is flowing west at a rate of 5. m/s. =etermine the >et4ski"s velocity

relative to the shore. %12 m/s ?2o0 of ect thrown into the air stops at the highest point in its path. !s it in e()iliri)m at

this point$ Explain. %:o, gravity is p)lling down&

. ect.

8. Explain :ewton"s second law in terms of inertia.

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9. -n astrona)t on the moon has a 11 kg crate and a 2+ kg crate. ow do the forces

re()ired to lift the crates straight )p on the moon compare with the forces re()ired to

lift them on Earth$

1. - freight train has a mass of 1.5 x 1#kg. !f the locomotive can exert a constant p)ll of

#.5 x 15:, how long wo)ld it take to increase the speed of the train from rest to 85

km/h$ %8 s&

11. - 5. kg )cket of water is raised from a well y a rope. !f the )pward acceleration of

the )cket is +. m/s2, find the force exerted y the rope on the )cket of water. %* :&

12. - oat moves thro)gh the water with two forces acting on it. ne is a 2.1 x 1+:

forward p)sh y the motor, and the other is a 1.8 x 1+: resistive force d)e to the

water.

a. 0hat is the acceleration of the 12 kg oat$ %.25 m/s2&

. !f it starts from rest, how far will it move in 1. s$ %12.5 m&

c. 0hat will its velocity e at the end of this time interval$ %2.5 m/s&

1+. - +. kg all is dropped from the roof of a )ilding 1#*. m high. 0hile the all isfalling to Earth, a hori;ontal wind exerts a constant force of 12. : on it.

a. ow far from the )ilding does the all hit the gro)nd$ %#2. m&

. ow long does it take to hit the gro)nd$ %*. s&

c. 0hat is its speed when it hits the gro)nd$ %*+.* m/s&

1. - 2. kg mass starts from rest and slides down a .8 m long inclined plane in .5 s.

0hat net force is acting on the mass along the incline$ %1+ :&

15. - #5 kg person escapes from a )rning )ilding y >)mping from a window 25 m

aove a catching net. -ss)ming that air resistance exerts a 95 : force on the person

d)ring the fall, determine the person"s velocity >)st efore hitting the net. %2. x 1 1

m/s&

1*. 'he parach)te on a race car that weighs 882 : opens at the end of a ()arter4mile r)n

when the car is travelling +5 m/s. 0hat total retarding force m)st e s)pplied y the

parach)te to stop the car in a distance of 11 m$ %45. x 12:&

1#. - 125 kg car is p)lling a +25 kg trailer. 'ogether, the car and trailer have an

acceleration of 2.15 m/s2directly forward.

a. =etermine the net force on the car. %2*9 :&

. =etermine the net force on the trailer. %*99 :&

18. - .15 kg aseall is thrown )pward with an initial speed of 2. m/s.

a. 0hat is the force on the all when it reaches half its maxim)m height$ %D1.# :&

. =isregarding air resistance, what is the force on the all when it reaches its peak$

%D1.# :&

19. 6ind the force exerted y each cale to

s)pport the *25 : ag in the diagram.

%1. x 1+:, 8. x 12:&

+#o

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2. - ox of ooks weighing +19 : is shoved across the floor y a force of 85 : exerted

downward at an angle of +5 elow the hori;ontal.

a. !f ketween the ox and the floor is .5#, how long does it take to move the ox

. m, starting from rest$ %2 s&

. !f ketween the ox and the floor is .#5, how long does it take to move the ox

. m, starting from rest$ %the ox does not move&

21. - . kg wagon is towed )p a hill inclined at 18.5 with respect to the hori;ontal. 'hetow rope is parallel to the incline and exerts a force of 1 : on the wagon. -ss)me

that the wagon starts from rest at the ottom of the hill, and disregard friction.

a. ow fast is the wagon going after moving +. m )p the hill$ %.9 m/s&

. ow fast is the wagon going after moving 8. m )p the hill$ %8. m/s&

22. - clerk moves a ox of cans down an aisle y p)lling on a rope attached to the ox.

'he clerk p)lls with a force of 185. : at an angle of 25. with the hori;ontal. 'he

ox has a mass of +5. kg, and the coefficient of kinetic friction etween ox and floor

is .5. 6ind the acceleration of the ox. %1. m/s2&

2+. - girl coasts down a hill on a sled, reaching the ottom with a speed of #. m/s. 'he

coefficient of friction etween the sled"s r)nners and the snow is .5, and the girl and

sled together weigh *5 :. ow far does the sled travel on the s)rface efore coming

to rest$ %5. x 11m&

Projectiles, Uniform Circlar !otion an" #ravitation

1. -n o>ect is thrown hori;ontally at a velocity of 18 m/s from the top of a cliff. !f the

o>ect hits the gro)nd 1 m from the ase of the cliff, how high is the cliff $ % 151 m &

2. -n o>ect is thrown from the gro)nd into the air at an angle of o

from the hori;ontalat a speed of 18 m/s.

-. 0hat is the maxim)m height achieved$ % *.82 m &

3. 0hat is the maxim)m range achieved$ % +2.5 m &

+. - st)dent standing 1. m from a tall )ilding. !f the st)dent throws a all at a velocity

of 12 m/s at an angle of +5 to the hori;ontal, at what height will the all hit the

)ilding$ % ass)me the all was thrown from gro)nd level & % 1 .92 m &

. - st)dent is standing on the top of a )ilding and he throws an o>ect into the air at a

speed of 1* m/s at an angle of 25oaove the hori;ontal. !f the )ilding is #5 m tall, how

far from the ase of the )ilding will the o>ect hit the gro)nd $ % *#. * m &

5. 'he fastest recorded pitch in Fa>or Geag)e 3aseall, thrown y :olan yan in 19#,

was clocked at 1*2.+ km/h %1.8 mi/h&. !f a pitch were thrown hori;ontally with this

velocity, how far wo)ld the all fall vertically y the time it reached home plate, 18.+ m

%*. ft& away$ %.89 m&

*. - all is fired from the gro)nd with an initial speed of 1.# x 1+m/s %approximately

five times the speed of so)nd& at an initial angle of 55. to the hori;ontal. :eglecting

air resistance, find %a& the all"s hori;ontal range and %& the amo)nt of time the all is

in motion. %2.## x 15m, 28 s&

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#. - person standing at the edge of a seaside cliff kicks a stone over the edge with a

hori;ontal speed of 18 m/s. 'he cliff edge is 52 m aove the water. ow long does it

take for the stone to fall to the water$ 0ith what speed does it strike the water$ %+.+ s,

+* m/s&

8. - daredevil is shot o)t of a cannon at 5. to the hori;ontal with an initial speed of

25. m/s. - net is positioned a hori;ontal distance of 5. m from the cannon. -t what

height aove the cannon sho)ld the net e placed in order to catch the daredevil$ %1.#

m&

9. - place kicker m)st kick a footall from a point +*. m %ao)t . yd& from the goal,

and the all m)st clear the crossar, which is +.5 m high. 0hen kicked, the all leaves

the gro)nd with a speed of 2. m/s at an angle of 5+ to the hori;ontal.

a. 3y how m)ch does the all clear or fall short of clearing the crossar$ %1. m&

. =oes the all approach the crossar while still rising or while falling$ %falling&

1. - spherical stone with a mass of 1.25 kg is attached to one end of a 9 cm string and is

the sw)ng in a hori;ontal circle. !f the maxim)m force that the string can withstand

efore reaking is 5 :, what maxim)m speed can e attained y the stone$ %18 m/s&

11. - satellite is located 1 km aove the s)rface of the Earth. ow long wo)ld it take

for the satellite to complete one orit of the Earth$ 0hat is its speed$ %**+1 s, #2+

m/s&

12. H)piter has a mass of 1.9 x 12#kg and a radi)s of orit of #.#8 x 111m. ect with a mass of 5. kg is sw)ng 22 times in 5#.5 s. !f the diameter of the

circle is *. m, what is the tension in the rope$ %8*.# :&

18. - merry4go4ro)nd is eing t)rned with a fre()ency of .25 ;. - child, with a mass of

kg, is sitting on the floor of the merry4go4ro)nd which has a coefficient of friction of

.+5. 0hat is the maxim)m distance from the centre where the child can sit witho)t

eing thrown off the merry4go4ro)nd$ Explain why the child wo)ld e thrown off.

%1.+9 m&

19. 'wo masses, 2 kg and 5 kg, are placed 2 m apart. - third mass of 5 kg is

placed in etween the two large masses a distance of 5. m from the larger mass. 0hatis the force acting on the 5 kg mass$ %*.+# x 1 4*: toward the 5 kg mass&

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!lti$le Choice %ection

1. Ise the following information to answer this ()estion.

-s an ice4dancer spins, a fringe on her cost)me sleeve ecomes detached.

=irection of otation

'he path it will follow, as viewed from aove, will e

a& !J

& !

c& !!!

d& !!

2. Ise the following information to answer this ()estion.

- plastic food ag in the space sh)ttle =iscovery appears to float motionless inthe air as the sh)ttle orits Earth.


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. 'he gravitational field aro)nd a planet varies

a& directly as the s()are of the distance from the planet"s s)rface

& directly as the s()are of the distance from the planet"s centre

c& inversely as the s()are of the distance from the planet"s s)rface

d& inversely as the s()are of the distance from the planet"s centre

5. 'he )niversal gravitation constant %K& was meas)red directly y

a& Lepler

& :ewton

c& Aavendish

d& 3rahe

*. - satellite in an elliptical orit

a& has )niform speed

& has the greatest orit speed when it is closest to the planet it is oritingc& has the greatest orit speed when it is f)rthest from the planet it is oriting

d& cannot e explained y the )niversal law of gravitation

#. - proposed design for an Earth space station wo)ld involve it rotating. 'he most

important reason for having a space station rotate is

a& it wo)ld give the inhaitants a night/day se()ence to keep their iological clocks

stale

& it wo)ld give the inhaitants a more complete view of the Earth elow

c& it wo)ld give the inhaitants a complete view of the s)rro)nding space so they

co)ld avoid eing hit y space M>)nkM

d& the centripetal acceleration of the station co)ld sim)late gravity for the

inhaitants

8. 6or a satellite in a circ)lar orit aro)nd the Earth.

a& the orital velocity m)st e smaller for a large mass

& the orital velocity will e the same for any mass

c& the orital velocity m)st e larger for a larger mass

d& f)el m)st e carried to provide energy to maintain the orital velocity

9. !n order to la)nch a comm)nications satellite and place it into a geosynchrono)s orit

aro)nd Earth, it is most important to control the

a& altit)de and speed of the satellite

& mass and si;e of the satellite

c& si;e and shape of the satellite

d& mass and altit)de of the satellite

F)ltiple choice answers

1. A 2. A +. 3 . = 5. A *. 3 #. = 8. 3 9. -

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Lesson 01 to 20 Review

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