Answer Key Chapter 2 - Henry County Schools

1 Chapter airplane travels at a constant speed, relative to the ground, of far has the airplane traveled after h in the air?d5vt5( km/h)( h)51800 long does it take for the airplane to travel between City A and City B ifthe cities are 3240 km apart?t5}dv}5} } a second plane leaves 1 h after the first, and travels at 1200 km/h, whichflight will arrive at City B first?t5}dv}5}13220400kkmm/h} hThe second plane arrives h after the first plane departs, so the firstplane arrives before the and your friend start jogging around a running track at thesame time. Your average running speed is m/s, while your friend runs at m/s. How long does your friend wait for you at the finish line?t5}dv}t155635 s (your time)t25} }5595 s (friend s time)Your friend s wait time is: 635 s2595 s }} m/sAnswer Key66 Supplemental Problems Answer KeyPhysics: Principles and ProblemsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, KeyPhysics: Principles and ProblemsSupplemental Problems Answer graph to the right shows the distance versus time for two cars traveling on a straight can you determine about the relative direction of travel of the cars?

2 The cars are traveling in opposite what time do they pass oneanother?They pass 5 h after car is traveling faster? A is traveling faster because the slope of its line has a larger magnitude. The slope represents }DDdt}, or is the speed of the slower car?The speed is equal to the slope of the line }DDdt}, which is calculated fromtwo points on the graph as 20 drop a ball from a height of m. It falls to the floor, bounces straightupward m, falls to the floor again, and bounces m. vector arrows to show the motion of the the top of the second bounce, what is the total distance that the ball has traveled? m m m m (m)Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 2 continued1234565010015020025030035040045 0500 Car ACar BTime (h)Distance (km) the top of the second bounce, what is the ball s displacement from itsstarting point?

3 Dd 5d11(2d2) 1d41(2d4) m m m m m the top of the second bounce, what is the ball s displacement from thefloor? m are making a map of some of your favorite locations in town. The streets runnorth south and east west and the blocks are exactly 200 m long. As you mapthe locations, you walk three blocks north, four blocks east, one block north, oneblock west, and four blocks a diagram to show your is the total distance that you traveled while making the map?dtotal5d11d21d31d41d553 blocks 14 blocks 11 block 11 block 14 blocks 513 blocks13 blocks3200 m/block 52600 your diagram to determine your final displacement from your blocks3200 m/block 5600 mThe displacement is 600 m east from the starting vector will you follow to return to your starting point?600 m toward the Key68 Supplemental Problems Answer KeyPhysics: Principles and ProblemsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 2 continuedAnswer KeyPhysics: Principles and ProblemsSupplemental Problems Answer antelope can run km/h.

4 A cheetah can run 117 km/h for short cheetah, however, can maintain this speed only for s before giving upthe chase. an antelope with a lead outrun a cheetah? d5vtt530 s vantelope5( km/h)1}36100hs}21}1010k0mm} m/svcheetah5(117 km/h)1}3610h0 s}21}1010k0mm} m/s 3 s 5750 m/s 3 s 5975 mThe cheetah can run 225 m farther than the antelope in s, so lead is not is the closest that the antelope can allow a cheetah to approach andremain likely to escape?226 m position-time graph to the right represents the motion of threepeople in an airport moving towardthe same departure person travels the farthestduring the period shown?person person travels fastest byriding a motorized cart? Howcan you tell?person B. The magnitude ofthe slope is largest for line Bwhen the person is person starts closest tothe departure gate?

5 Person B and person C start400 m from the person appears to be going to the wrong gate?person CCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 2 continued5010015020025030050040030020010 00100200300400500 ABCTime (s)Displacement from gate (m) radio signal takes s to travel from atransmitter on the Moon to the surface ofEarth. The radio waves travel at What is the distance, in kilometers,from the Moon to Earth?d5vt5( ) 3 s5 ( ) 3 1}1100k0mm}25 start to walk toward your house east-ward at a constant speed of km/h. At the same time, your sister leaves yourhouse, driving westward at a constant speedof km/h. The total distance from yourstarting point to the house is a position-time graph that showsboth your motion and your sister the graph, determine how longyou travel before you meet your far do you travel in that time?

6 Bus travels on a northbound street s at a constant velocity of stopping for s, it travels at a con-stant velocity of m/s for s to thenext stop, where it remains for s. Forthe next s, the bus continues north at a d-tgraph of the motion ofthe is the total distance traveled?d5v1t11v2t21v3t31v4t41v5t55( m/s)( s) 1( m/s)( s) 1( m/s)( s) 1( m/s)( s) 1( m/s)( s)5875 is the average velocity of the busfor this period?vave5}DDdt}vave5 m/s875 m} st (s)d (m) (h)Distance from house (km) Key70 Supplemental Problems Answer KeyPhysics: Principles and ProblemsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 2 continuedAnswer KeyPhysics: Principles and ProblemsSupplemental Problems Answer Key71 Chapter the velocity-time graph below to calculate the velocity of the object whosemotion is plotted on the is the acceleration between the points on the graph labeled A and B?

7 A5}Dtv}5 }(vf2tvi)} is the acceleration between the points on the graph labeled B and C?Dv50, therefore a 50 (no acceleration) is the acceleration between the points on the graph labeled D and E?a5}Dtv}5}(vf2tvi)}55 2125 is the total distance that the object travels between points B and C?d5vt m/s s you throw a ball straight upward, it will rise into the air and then fall backdown toward the gound. Imagine that you throw the ball with an initial velocityof m/s}}} m/s}}} (s)Velocity (m/s)Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, long does it take the ball to reachthe top of its motion?vf5vi1 attherefore tf5}vf2avi} far will the ball rise before itbegins to fall?d5}12}(vf1vi)t5}12}( m/s)( s) m is its average velocity during thisperiod?

8 Vave5}df2tdi}5} m} m/s car is traveling at 20 m/s when the driversees a ball roll into the street. From thetime the driver applies the brakes, it takes 2 s for the car to come to a is the average acceleration of thecar during that period?a5}Dtv}5}vf2tvi}5}0 m/s22s20 m/s}5 210 far does the car travel while thebrakes are being applied?d5di1vit1}12}at250 m1(20 m/s)(2 s) 1}12}(210 m/s2)(2 s)250 m 140 m 1(220 m/s)520 hot air balloon is rising at a constantspeed of m/s. The pilot accidentallydrops his pen s into the flight. far does the pen drop?The pen falls from the altitude of theballoon at 10 ( m/s)( s) fast is the pen traveling when ithits the ground, ignoring air resistance?vf25vi212a(df 2 di)5012( m/s2)( m m)5196 m2/s2v m/s sudden gust of wind increases the velocityof a sailboat relative to the water surface m/s to m/s over a period of is the average acceleration of thesailboat?

9 A5}Dtv}5}(vf2tvi)} far does the sailboat travel duringthe period of acceleration?df5di1vit 1}12} m1} }1}12}( m/s2) ( s)25130 a serve, a tennis ball leaves a racket at180 km/h after being accelerated for ms. is the average acceleration on theball during the serve in m/s2?vf5(180 km/h)1}1010k0mm}21}36100hs} m/s}}} m/s}}} m/s2 Answer Key72 Supplemental Problems Answer KeyPhysics: Principles and ProblemsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 3 continuedAnswer KeyPhysics: Principles and ProblemsSupplemental Problems Answer Key73a5}Dtv}5}vf2tvi}55630 far does the ball move during theperiod of acceleration?df5di1 vit1}12} m1( m/s)( s) 1}12}(630 m/s2)( s) walks off the end of a is her acceleration in m/s2towardthe pool?Her acceleration due to gravity long does it take her to reach thewater?

10 Df5di1vit1}12}at2, viand di50 Solve for t:t5!}2ad} 5! is her velocity when she reachesthe water? m/s 1( m/s2)( s) rocket used to lift a satellite into orbitundergoes a constant acceleration of m/s2. When the rocket reaches an altitude of 45 km above the surface of Earth, it is traveling at a velocity of 625 m/s. How long does it take for therocket to reach this speed? Solve df5di1vit1}12}at2for t(let viand di50)t5!}2ad} 5! 5120 table below shows the velocity of a student walking down the hallway betweenclasses. is happening to the student sspeed during s and s? He is slowing is his acceleration between t510 sand t520 s? a5}Dtv} is his acceleration between s and s?a5}Dtv}5}vtff22vtii} m/s}}} m/s}}}200 s2100 svf2vi}tf2tiTime (s)Velocity (m/s) (2345 km)1}1010k0mm}2}} m}} m/s}}} Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, 3 constant acceleration, how fardid he walk during the first 5 s?