mechanics 1.1 test answers

8/4/2019 Mechanics 1.1 test answers

1/22

.AMERICAN ACADEMYLARNACA6 PHYSICS: SEMESTERl: TEST ..,Advanced Level - AS

~ U = m = = t = l = - : - = P - = h : . ; _ l Y - = - l s = - = i c = s - = o = n : _ _ : t = h = - = e : _ _ : G = - o = - = : : . _ : T ~ o : J 'P c . : : i = - c - = l : _ _ = M : = . . . . : e = - = c = h = a = n = - = i c = s ~ ( L A = . J . "~---h;"JlT i m e : 1 h o u r 2 0 m i n u t e s , " J i f .~==~~~~~==~~~~~ ~~~~~~~IC~,"Writeyour(na.m.ehere. ) ~ J J s : r n : : e1 / . Wtite theidate .bere

I Other names

You must haveScientific calculatorRulerProtractor

G R A D E

Instructions Use black ink or ball-point pen (blacklblue). Fill in the boxes at the top of this page with your names and the date. Answer all questions (there are 21 questions and 1 challenge / bonus question). Answer the questions in the spaces provided - there may be more space than you need. In calculations you should show all the steps in your working, giving your answer at each stage.Information The total mark for this paper is 73 (+ 10bonus marks). The marks for each question are shown in brackets - use this as a guide as to how much time to spend

on each question. Questions labelled with an asterisk (*) before the number of the question, are ones where the quality

of your written communication will be assessed - you should take particular care with spelling,punctuation and grammar, as well as the clarity of expression, on these questions.

Questions with an asterisk (*) after the number of the question are challenge questions. They aremore searching and deeper and they are intended to challenge your knowledge and understanding ofphysics. They are bonus questions and you should attempt them only if you have time.

The list of data, formulae and relationships is provided separately. You may use a scientific calculatorAdvice Read each question carefully before you start to answer it. Keep an eye on the time. Try to answer every question. Always check your answers.

Turn over


2/22

-2-Questions 1-10: Choose the right answer from choices A, B, Cor D.

~ . The acceleration of free fall on Mars is 3.7 m S-2.If an object on Mars is launched vertically upwards with an initial speed of 40 m S-1, itsspeed after 3.0 s will be

i J , . : = I . . r - I A . , . . .0 A 11 mS-1 --k,[ s g B 29 m S-1 V = I . A . . . - + - o . . . ~0 C 36 m S-1 - 40 ~c; .-I-\- l-"3.t-~>-'- : > . : ~ ' O S ; )51 m S-1 -.0 D

-

~ A ball is dropped from rest from a building 35.0 m high.If air resistance is neglected the ball hits the ground with a speed of0 A 8.4 m S-1 \j"- ""~ " 2 . . ~ , s= v . . . . . . .0 B 13.1 m S-1 \r"'\.. :l. "'" 1 ' ~ l - v \ c ; . -"'l,.. -< > c , . f ) w . . . .- . : :0 C 18.5 m S-1 U"" -;Lg D 26.2 m S-1

J) Which table is correct for scalar and vector quantities?~.~,.-0 A has magnitude has a direction./ ./..-...c-

VCI.'LVI X ./

0 B ! has magnitude has a directionscalar X ./ ivector ./ ./

~ C has magnitude I has a direction! scalar ./ : Xvector ./ ./

~ D : I has magnitude has a directioni scalar i ./ ./ l .: ./ :\ vector . : X

. . . 1 3


3/22

-3-

Use the following information to answer Questions 4 and 5.A body is acted on by a vertical force of 18 N and a horizontal force of 32 N.~ The angle to the horizontal of the resultant force is given by0 A cos' (18/32)B B tan:' (18/32)0 C sin:' (32/18) ~-\ l: n . . . -O D tan" (32/18)

5) The magnitude of the resultant force in N iso A 32 + 18o B 322 + 182o C -J32+18[ 2 ( ' D ~322 +182

~ A passenger, sitting on a t rain and facing the engine at the front of the train, has abowl of thinsoup on the table infront of him. The train decelerates as it enters a station. Which sketch bestrepresents the level of the soup inthe bowl?

B. c. D.

. . . / 4


4/22

-4-

A child goes down a slide. Which of the diagrams correctly represents the forces actingon the child?

A B C D

~ Ao Bo Co D

In questions & -7, which of the following statements best completes the sentence.A decreases linearly from zeroB increases from zero to a maximumC increases linearly from zeroD stays constant at a non-zero value

Choose the appropriate letter to indicate which statement best completes the sentence.Each answer may be used once, more than once or not at all.~ If air resistance is neglected, the horizontal velocity component of an arrow fired from abow with distance travelled

OAo Bo CI : 2 S D

~ The velocity of a ball bearing falling from rest through syrup with distance fallenOA~Bo COD

.. ./5


5/22

-5-

/~ A weight W is hung from a wire stretched between two fixed supports as shown. The tensionin the wire to the left of the weight is TL and that to the right of the weight is TR. Which of thefollowing is correct?

(Total for Questions 1 -10 = 10 marks)

.. ./6


6/22

-6-

I) The velocity-time graph below is for an object undergoing constant acceleration a.velocity

v -------------------------------------------------~

. .IIIII

yO~----------------------------------------~t---time

Which of the following statements about the areas X and Yare correct?Put ticks (.1') in the tw o correct boxes.

X= ut DX= ~ut DX = ~at2 0Y = ut [Z ]Y = ~vt DY = ~at2 D [2]

(Total for Questions 11= 2marks)

. . . 1 7


7/22

-7-I~ A stone is thrown vertically upwards at 12mS-1.

(a) Calculate the speed v of the stone when it is 3.0m above the point of projection.u= 9.8ms-2U-::. t 1. . ' 1 1 \ > - ,

o . . . _ _ . : : : - , . < 6 ' ' 1 ; \ > -"I,...~ ~ 1,0o . A . . .",-IS':; ~

If'l.. -; v . . . ." ' - ~ " ? - . C l s= - (\1."",s.-') '"t. + l 1 . x -q.~..,....-1..)


8/22

-8-

1 3 ) A small aircraft flies at a velocity of 200 km h-1 relative to the ground.There is a wind blowing at 50kmh-1 from the west.The pilot wishes to reach a destination due north ofthe starting point.Find the resultant speed vof the aircraft, and theangle e , west of north, which it must take. 200km h-

1

:kro~\-' J~~~ " ' "\J " - : : : :2 .\St.:)'- ko.4l. . \ . . - ' \9 :; ~-'~ :: ~' 1.

"2.\10 tt

(Total for Question 13 = 5 marks)

v= 'b.9.Y..~.~~~ .e = . \ f . - \ . oW of N ,

Show your working clearly.You may wish to draw a vector diagram.

50km h-1. .

.. ./9


9/22

I , Answer the following questions with an example where possible:(i) Can a body to be accelerating while travelling at constant speed ?(ii) Can a body have a constant velocity an d a varying s peed ?(ill) Ifa body has zero velocity, can it be accelerating ?(iv) Can a body be accelerating ina direction opposite to its velocity ?

-- - -

\\ ....~5_ ,i \ : ~ ~ ch~\~ ,*l~C~ Jf,.~ . C~~\.~ 'v\Q \...~ ~ cL ~-..~ ~Q g ~ A e

. 1 ' - ' 0\'\,~ b ~w~QAl t :> J.\.~; :> ~'-r A A ,,",6 t5~~

iii, YE5~ ~ 5 \ 0 . . \w.. .~ W ~J.~ "'VI; ~ h i2!.s..u1 ~lr )ce 'b' ().A o\;~W ~ ~O~

.~ \:'\. ~f,J ~


10/22

-10-J ~ A student is required to measure the speed of a trolley rolling down a slope. This could

be done using a ruler and stopwatch but the student prefers a method using ICT.(a) The student uses a light gate as shown in the diagram.

Describe how the student obtains the measurements needed to calculate speed.

~Lightgate

,\~~~ "~'\\~"'\"~~'~""~\"~ """"''''''''' '"''''''''', , , . . ' ,, , , ,, , , ",~,~"",\Y"""",~~ )f "",,,,\~~,,,,.b~k,,,~,,,,,,,,~,, ""~ '~ '~ "'':> '" . '''''''''''' ""'"

\)~, "b~\e~"",,,,~"-~\~,t.\C ,'

(b) The student thinks that the stopwatch method is less reliable than the ICT method.Discuss what makes using a stopwatch less reliable.

"""",,,,,,,,,,>~,.(A.,~,,,,,,,,,~,, "".",\~"""""\N:o:,r.!h;~,, ' """"""""'""",,,.~,,,,~,,k~~, """"~~,t"~"",k,~,,,,,,,,,,,,,,,,

(Total for Question 15 = 4 marks)

...Ill


11/22

-//-

*f~ During a lesson on Newton's laws of motion, a student says, "We don't really need tobother with Newton's first law because it is included in his second law".State Newton's first two laws of motion and explain how Newton's second law includesthe first law.

...................l...~ \r. ~ ~\:., ~ ~.E ;: b .- -s:-..................0 u.. \: : : = . ~ .

. . . . . . . . . . . . . . . . . . . .E . : :i. . . :;: ~ ..~ ..t ~t:: 0...................................................... I.~ .= , ( ) . . _ = O ( \ f = - 1.......... , , , ", ~ , , , .

- f '...J'\'............................................ ~ _ .

. ._~.__ __Q'otal for Question 11 = 5 marks) .. _

- ..


12/22

-/k

Ii) A boy throws a ball vertically upwards and lets it fall to the ground. Figure 1 showshow displacement relative to the ground varies with time for the ball.Figure 1

displacement

ground levelto time

_ (a) (i) State which feature of a displacement-time graph represents the velocity ............!!J~~.~ .

(1 mark)(ii) On the axes below, draw the shape of the velocity-time graph for the ball betweento and t2. The starting point is labelled X. .

(3 marks)velocity

x a_-- ___

o timeto

' ../13


13/22

-/3-(b) Figure 2 shows the ball deforming as it contacts the ground, just at the point where it is

stationary for an instant and has reached maximum deformation.Figure 2

centre of mass

. ,(i) Explain how Newton's third law of motion applies to Figure 2.. . . . . . . . . . . . . ~ ~ ~ '" \ 0 \ . 1 : " ? ~ ; .~ ~ . ~ ~ .............. \~\\ ~ ~.~~~ ..~ b~~

(2 marks)(ii) Explain why there is a resultant upward force on the ball in Figure 2.

..............~~.~ ~.~ -e ? ~.~\.~~~ .

...... ~.t.~.\; ..: > ~ ~. ~..u ..~ .(2 marks)


14/22

Ig (a) Define the newton ............ ~~ ~ l..~ ~ ~ b .............!-:-~ .~k . ~ 1~.~.::~...........................................................1]

(b) Fig.t8.1 shows a spaceship on the surface of the Earth.

Fig.lt1The mass of the spaceship is 1.9 x 106 kg. During lift;o ff, the spaceship rockets produce avertical upward force of 3.1 x 107N.(i ) Calculate the weIght of the spaceship.

\ J....) : ; " ' \ A . ! ! >' : : " \ . ' ( > < \0t o k~ x ~.~\ f\J ~__\

E .weight = J . 1 . . . ~ ~.9 . t : ! . , [1]


15/22

-/5-(ii) Calculate the initial vertical acceleration as the spaceship lifts off.

. _ b . " 7 -"L.acceleration - 7...~.~ .(iii) The vertical upward force on the spaceship stays constant. Explain why the acceleration

of the spaceship increases after lift off .. . . . . . . . . . . . . . . . . . . . ~ . .~ ~ ~ ~ )~ .. . . . . . . . . . . . . . ~ . . . 9 .- : - : t ..................................................................................................................................... [1]

[Total: 5]

[2]


16/22

-16-(?) Fig.J


17/22

-/r--(iii) Calculate the velocity of mass B after falling 1.40 m.

\r'to - = u . . . _"t..!.,; 2.. " , - Su- -::J :2.. Q \. < ;.

~ 1 2 . . 0 ; < : \ . 0'( - I > \ . s,_' to. " )< t . t' ~o I A t \ .velocity = J:.1.~.~.~.~~ ';~ [2]- - . . .

(iv) Mass B hits the floor at a speed of 2.47ms-1. It rebounds with a speed of 1.S0ms-1.The time of contact with the floor is 3.0 x 10-2 s. Calculate the magnitude of the averageacceleration of mass B during its impact with the floor.

\- So "'-\c;\ -l- Z 4 -=1 " \. (s . _ I , )10 >c " l0_.,..

acceleration = J3.~.~.~: : : : :- . .. . .. . .. . .. . .. . .. . .. ~[2][Total: 9]

r. _/(g


18/22

-/8-'< '0 This question is about a sport called kitesurfing (Fig.ltJ.1).

kite

boardFig. 10.1

The kitesurfer stands on the board, and is pulled along the surface of the sea by the lines attachedto the kite.The kitesurfer, lines and board are modelled in the diagram in Fig. 2..0.2.

kitesurfer kite linesboard

Fig.,.tO.2(a) The total tension in the kite lines is 1000 N.

By scale drawing or calculation, show that, when the angle e = 30, the horizontal force pullingthe kitesurfer is about 900 N.


19/22

-19-(b) (i) Explain why the kitesurfer in this situation needs to have a mass of more than 51 kg. Your

answer should refer to the components of forces.g= 9.8ms-2 S,'" "?o"

A~\",", :. l \ T U ' O J0 "" ~ '::: Socru,Jt . t . . . v . . . .


20/22

- . 2 . -

; 1Y The photograph shows a solar-powered model boat built by some technology students.\\

\

This boat has a solar-powered fan attached. The fan blows air towards the sail.(a) The technology students explain to a physics student that the fan exerts a force on

the air and the air then exerts an equal force on the sail to drive the boat forwards.Assume that these two forces are equal for the rest of the question.The physics student tells them that according to Newton's laws of motion this willnot work.(i) Identify the Newton's third law force that pairs with the force of the fan on the

aIr.

. .. . .. . .. . .. . . .. . .. . .. . .. . . ~ .~ ~ .. fJ.\~ c ~ ~ .

(ii) The boat is placed in the water and the fan switched on. The boat remains atrest.Add labelled arrows to the diagram below to show the four forces acting on theboat in this situation. i

+--1~"c6 o~ M~().u ~A'L

I I

.. ~2/


21/22

-.2../-*(iii) Use Newton's laws of motion to explain why the boat does not move

horizontally .

...~..........~\C..........~-:I ~ ~~ ~ aA._ O'~.v ..~~~ 5 \ ~ l

(b) The physics student suggests that the boat is more likely to work if the fan isreversed to point in the opposite direction.Explain this suggestion .

...................... ~. ..~\M.~().~L. ....~t~'V~ .

. . .:: .7JA~'i... . . . . . .~.W?~

(Total for Question II=9 marks)" . _ . . . , " " " ' ; _ ~ . ~ . ~ . . . . . . - . ._ _ , . _ . . _ = _ . . ~.""_~"'._=~ ..


22/22

22

22)* The diagram shows a particle A of mass 0.5 kg suspended by a vertical string.A particle B of mass 0.4 kg is suspended from A by means of another string.A force of ION is applied to the upper string and the particles move upwards.Find the acceleration of the system and the tension in the lower string.

JO N

A OSkg

B 0.4 kg

-

~E : : = c "!A.. IA.T - l c r 4 - \

mechanics 1.1 test answers

Documents