AHS 2024 Prelim Ans (P1/P2)

2 0 2 4 A H S S 4 P h y s i c s P r e l i m E x a m P a p e r 1 A n s w e r s 1 2 3 4 5 6 7 8 9 1 0 C A D B D C D B B C 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 A B A C D A D C C D 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 A D D D C B A C C D 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 C A B B B A B A C B P a p e r 2 A n s w e r s 1 ( a ) S p e e d i s a p h y s i c a l q u a n t i t y w i t h o n l y m a g n i t u d e b u t v e l o c i t y i s a p h y s i c a l q u a n t i t y w i t h b o t h m a g n i t u d e a n d d i r e c t i o n . O R S p e e d i s a s c a l a r q u a n t i t y . V e l o c i t y i s a v e c t o r q u a n t i t y . 1 ( b i ) c h a n g e i n s p e e d = 2 5 - 2 2 = 3 . 0 m / s 1 ( b i i ) c h a n g e i n v e l o c i t y = 2 5 - ( - 2 2 ) = 4 7 m / s o r - 2 2 - 2 5 = - 4 7 m / s 1 ( c i ) a v e r a g e a c c e l e r a t i o n = c h a n g e i n v e l o c i t y / t i m e = 4 7 / 0 . 0 0 1 3 = 3 6 2 0 0 m / s 2 ( 3 s . f . ) o r 3 6 0 0 0 m / s 2 ( 2 s . f . ) [ a c c e p t E C F f r o m ( b ) ] 1 ( c i i ) a v e r a g e f o r c e = m a s s x a c c e l e r a t i o n O R = 0 . 1 6 x 3 6 0 0 0 = 5 7 6 0 N ( 3 s . f . ) o r 5 8 0 0 N ( 2 s . f . ) a c c e p t E C F f r o m ( c i ) ] 1 1 2 ( a ) F o r c e a c t i n g o n e a c h c y l i n d e r F = 8 0 0 / 4 = 2 0 0 N P r e s s u r e i n c r e a s e = F / A O R = 2 0 0 / 0 . 0 0 3 5 o r 8 0 0 / ( 4 x 0 . 0 0 3 5 ) = 5 7 1 0 0 P a ( 3 s . f . ) o r 5 7 0 0 0 P a ( 2 s . f . ) [ A w a r d 1 m f o r m e t h o d e v e n i f a r e a i s c o n v e r t e d w r o n g l y / E g . 3 5 c m 2 i s w r o n g l y c o n v e r t e d t o 0 . 3 5 m 2 ] 1 1 ( b ) T h e c o n t i n u o u s b o m b a r d m e n t / c o l l i s i o n o f a i r m o l e c u l e s o n t h e c y l i n d e r w a l l e x e r t s a f o r c e ( p e r u n i t a r e a ) o n t h e c y l i n d e r w a l l . 1 ( c ) T h e g a s m o l e c u l e s g a i n k i n e t i c e n e r g y / m o v e f a s t e r . T h i s c a u s e s t h e m o l e c u l e s t o b o m b a r d o n t h e c y l i n d e r w a l l m o r e f r e q u e n t l y w i t h a n d m o r e f o r c e f u l l y a n d h e n c e t h e r e i s a g r e a t e r ( a v e r a g e ) f o r c e p e r u n i t a r e a o n t h e c y l i n d e r w a l l . T h e r e f o r e , t h e g a s p r e s s u r e i n c r e a s e s . 4 p o i n t s – 2 m a r k s , 1 - 3