Lets play a game( might help students appearing in physics 12 and 22)

[Aly Emran]

the game is we all would ask difficult questions related to physics ( not off the syllabus once) and others would answer with logics and reasoning! i'll start first: (questions can be from past pprs)

1.Which does not normally use infra-red radiation?
A electric grill
B intruder alarm
C television remote controller
D sunbed

2.A garden table weighs 40N and has a top surface of area 2m
2 metre square. It is raining and the rain produces
a pressure of 4N/m2 metre square on the table.
What is the force exerted by the table on the ground?
A 20N
B 32N
C 42N
D 48N

3.The background count rate in a laboratory is 10 counts/min.
The measured count rate from a radioactive source is 410 counts/min, which includes the
background.
The half-life of the source is 5 days.
What is the measured count rate after 15 days?
A 10 counts/min
B 50 counts/min
C 60 counts/min
D 110 counts/min

 

[Sparky123]

MashaAllah I did it;
1D because sunbed has uv rad. not infrared
2D because 4x2=8 N due t rain + W of table=48N
3C because count rate of rdactv matrl= 410-10=400, half life occurrence may be 3 times in 15 days as 15/5=3 and count rate= 50+10(background rad.)

 

[M.Omar]

explain oct/nov 2012 session mcq abt the plane....where they ask abt the greatest force.......?um would know check it out.

all correct now u ask difficult questions and i'll try
what intruder alarm runs on?

 

[M.Omar]

this vertical acceleration is actually the lift frm the ground...aeroplane still not lifted....however the force on wheels =weight of aeroplane newtons third law right?...so whyh is weight largest force when the force on wheels frm grnd is equal........i know this just wanna know how u explain...dude there is no mention of frictional force in tht question nor does it matter

 

[M.Omar]

exactly i thought of questioning but diagram cannot be mentioned. so the answer is d. weight of the aeroplane becaus acceleration is 2m/s2 so the frictional force would be less. there is no vertical acceleration present so d. is the answer

reply above

 

[M.Omar]

exactly i thought of questioning but diagram cannot be mentioned. so the answer is d. weight of the aeroplane becaus acceleration is 2m/s2 so the frictional force would be less. there is no vertical acceleration present so d. is the answer

reply bro

 

[M.Omar]

idk much but i guess due to gravitational strength the force in direction of strenght is greater this confused me cox i nver thought about that

the force exerted by ground would equal force due to weight......right?.........or not?.........explain..it,ll be fun

 

[Waleed Mir]

Forces of 30N and 50N act on the same body but in different directions. Which value could not be the resultant force on the body?

A 10N B 30N C 50N D 70N

 

[M.Omar]

force=ma or W/10(i.e mass)*a
so the thrust force by plane = W/10 *2(acceleration given in question)=W/5
The weight is W which is greater than w/5 tht is its thrust......
the lift force is smaller than weight because the aeroplane does not take off.......so lift force not greater than weight........finally force frm grnd is not equal to weight because the lift force actually has a share in upward force along with force frm grnd.....so equation=force frm grnd+lift...........so weight is actually equal to collectively force frm grnd and lift.......and individually weight is greater than the other three

 

[Waleed Mir]

What would be the explanation to the MCQ's answer (A.10)?

 

[Waleed Mir]

Maybe I didn't explain myself correctly. Taking 10N as the force which cannot be possible, how do we get the other three values which are infact possible? What would be the explanation for them. That is the real problem.