circular motion- sl- m

8/18/2019 Circular Motion- SL- M

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1. (a) (i) from satellite towards centre of Earth;

(ii) tangent to circle at satellite in correct direction;

(no labels, [1 max] ) 2

(b) direction of motion is changing / force acts on satellite;

and changing direction means changing velocity / any further detail; 2

(c) work done is product of force and distance moved in direction of force;

force is always normal to direction of motion;

hence no work done;

(accept argument based on changes in E k and E p) 3

[7]

2. [1]

3. (a) Look for an answer on the following lines!

the direction of the car is changing;

hence the velocity of the car is changing;

or

since the direction of the car is changing;

a force must be acting on it, hence it is accelerating; 2 ma"

(b) (i) arrow pointing vertically downwards; #

(ii) weight;

Do not penalize the candidate if they state “gravity”.

normal reaction; 2

Do not penalize the candidate if they state “push of thetrack on the marble”.

(iii) loss in PE = 0.05 $ #% $ (%!& ' %!3);

gain in *E 2#

mv 2;

to give v = 3.0 m s '#

;or

use of v = gh2

to give v = 4.0 m s '#

at point B;

and ten use of v 2 ' u

2 = 2gh !it v = 4.0 m s

'# and h = 0.35 m;

to get u = 3.0 m s '#

; 3 ma"

Do not penalize the candidate if g = 9.8 m s –

is used.

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(iv) recogni#e tat resultant force = r

mv2

;

= #+!%

)%!,%!%( ×

= 2.$ %;

% = r

mv 2

' mg ;= 2.$ ' %! 2!# -; .

[12]

4. &[1]

5. (a)

e l e c t r o nc h a r g e e

p r o t o nc h a r g e e

/

0

1 ' 2

(i) correct ';

(ii) correct ;

(*) F = k 2

2

!

e

or F =2

2

. !

e

oπε ;

Accept if answer is seen in c!.

"


3/4

(c) F = k !

mv

!

e 2

2

2

=;

to give # =2

2

mv

ke

;

correct su*stitution # =#223#

3&2

#%)2!2(#%#!,

#%)3!#(#%,

×××

×××

−

−

to give # = 5.2 $ #% '##

m; 3

(d) Answers will $e open%ended $ut essentially look for a description of either emission or a$sorption spectra eg !en elements in teir gaseous pase (state) are e"cited te+ emit ligt ,discarge tu*es emit ligt;!ic as a series of !ell defined !avelengts;te !avelengts are caracteristic of te element;te e"istence of tese caracteristic !avelengts support te idea of atomic energ+ levels; 3 ma"

[9]

6. (a) for circular motion- force reuired to!ards centre of circle , centripetal force;tis provided as a result of e"tension of te spring; 2

Do not give credit where candidate implies that the spring is pulled outwards $y a force.

(*) force produced *+ spring = .5 $ #& 2+ -;

use of F = r

mv2

;

2/ = 23!%

)%+!%( 2v×

;

v = .// m s '#

; 4[6]

7. (a) (i) spacing of te dots is increasing , &'(() ;

(ii) tree furter dots;spacing increases *+ t!o suares *et!een an+ t!o dots; 2

(iii) distance = 3/.$ m;

(*) (i) travels (2.2 $ . ) &!& between drops;

speed

=

&%!%

&!&

m s '#

; 2

*


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(ii) in eac 0.10s speed increases *+ &%!%

)..!%( ×

= 2.0 m s '#

;

acceleration =

=

&%!%

%!2

2.5 m s '2

; 2

or

in (2 $ %!&%) seconds, distance traveled is 3!2 m;

a =22 )!#(

2!32)(2 ×=

∆

t

s

= 2.5 m s '2

; Allow a different choice of appropriate time interval to givecorrect answer.

[8]

+

circular motion- sl- m

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