(i) The diameter of neck and bottom of a bottle are 2cm and 10cm respectively. The bottle is completely filled with oil. If the cork in the neck is pressed in with a force of 1.2kgf, what force is exerted on the bottom of the bottle?(ii) A ball is thrown vertically upwards. It returns 6s later. Calculate : (i) the greatest height reached by the ball, and (ii) the initial velocity of the ball. (Take g = 10metre per second square).

1
by NiDalas5usanchaw9rah

2015-12-05T22:05:16+05:30
THIS IS THE ANSWER OF 2ND PART
WHEN BALL IS THROWN UPWARDS THE FINAL VELOCITY IS ALWAYS 0
AND I AM TAKING g=10M/SEC2  SO USING 1 EQUATION OF MOTION
HERE TOTAL TIME IS 6
WE KNOW TIME OF ASCENT=TIME OF DESCENT
i.e TIME TAKEN TO REACH UPWARDS= TIME TAKEN TO COME DOWN
SO TIME TAKEN TO REACH UP IS 6/32=3 SEC
V=U+AT
0=U+(-10)*3
-U=-30
U=30 M/SEC
SO, INITIAL VELOCITY IS 30
NOW TO FIND HEIGHT WE USE 2ND EQUATION OF MOTION
S=UT + 1/2 (-g) T²
S=30*3-1/2*10*9
S=90-45
S=45m

THIS IS THE ANSWER FOR 1ST PART (300N)
WE KNOW IKGF=10N SO
1.2KGF= 1.2*10=12N
NOW P=FORCE/AREA
P=12/ (22/7*1*1)            (WE ARE ASSUMING THE CORK AND BASE AS A CIRCLE)
IN THE ABOVE EQUATION WE TOOK RADIUS AS 1 AND WHOLE AREA IS ﻿πR²
SO THE PRESSURE IS 42/11 PASCAL
AGAIN USING SAME FORMULAE P=F/A
NO W P=42/11
AND AREA IS (22/7)*5*5
WE CAN FIIND THE FORCE WHICH COMES OUT BE 300N

THEIR CAN BE A SLIGHT MISTAKE IN THE ABOVE ANSWER BUT THE STEPS I HAVE DONE IS 100% CORRECT