Biology; Chemistry; Physics: Post your doubts here!

[princex]

i could'nt understand organic chem ix dere easy way or tecnique 2 solv past paper????plxx helppp

 

[ritesh isuri]

i could'nt understand organic chem ix dere easy way or tecnique 2 solv past paper????plxx helppp

well that depends on the question and i do not think there is a shortcut to learn organic

 

[princex]

uff ab kia hoga acha kasy learn karein??

 

[ritesh isuri]

uff ab kia hoga acha kasy learn karein??

just try to work out some questions and when u have difficulties post the question here and i'll help u

 

[Mars-on-Earth]

i could'nt understand organic chem ix dere easy way or tecnique 2 solv past paper????plxx helppp

Organic chemistry is very easy once you understand it. Just go through your text or notes once and try to visualize in your brain and keep writing it down. If you know the general formulas, the rest is pretty easy. Consult your teacher once to explain it to you again after you read it... No shortcuts in this

 

[Mars-on-Earth]

Whats the easiest way to learn the numericals of Moles???

Unitary methode. The formulas are just to confuse you, they should only be remembered when you know the basics. The CIE workshop teachers say that CIE prefers simple unitary method for students, everyone understands it. Like if you want to know mass of two moles of carbon, you do
1mol= 12g so 2mol= 2x12=24g
Instead of memorized formulas. Though there are some formulas that do need to be learned

 

[robinhoodmustafa]

Why Amylase Solution is Used rather than Saliva in a Test?

 

[Mars-on-Earth]

Why Amylase Solution is Used rather than Saliva in a Test?

Concentration difference. Saliva has a small amount of amylase enzyme that is why only some starch is converted to glucose in the mouth, the rest in the small intestine. Amylase solution would be more efficient for test to get the best results.
Plus how much saliva is there for tests upon tests?

 

[CoolBreeze]

I just studied Newton's third law. It says that there is an equal and opposite reaction to every action so won't that reaction cancel out the action causing the object to stay in rest???

 

[Mars-on-Earth]

I just studied Newton's third law. It says that there is an equal and opposite reaction to every action so won't that reaction cancel out the action causing the object to stay in rest???

If the object were to stay in place then there would be no action to have a reaction to in the first place.
The third law applies given that an action has already taken place. Example if a ball is moved with 2N force, the friction force against it would be equal(2N) and opposite (stopping it) and the ball would eventually come to rest.

 

[CoolBreeze]

A car of mass 1000kg is accelerating at 2 m s^-2. What resultant force acts on the car? If the resistance to motion is 1000N, what is the force due to the engine?

 

[Mars-on-Earth]

A car of mass 1000kg is accelerating at 2 m s^-2. What resultant force acts on the car? If the resistance to motion is 1000N, what is the force due to the engine?

F=ma, so the resultant force would be 2x1000= 2000N.
And if the car is accelerating then the resistant force is cut out. 2000N-1000N= 1000N. That is the force applied by engine.
Am I correct?

 

[CoolBreeze]

For chemistry, should I consider reading "A New Certificate Chemistry by holderness & Lambert" for O' levels or should I just stick with Chemistry Matters by Chen Ling Kwong?

Try Chemistry Insights by J G R Briggs....Its the best book!!!

 

[ritesh isuri]

F=ma, so the resultant force would be 2x1000= 2000N.
And if the car is accelerating then the resistant force is cut out. 2000N-1000N= 1000N. That is the force applied by engine.
Am I correct?

no it is not good the force applied due to engine is 3000N. from the equation F=ma, we get the resultant force and for the resultant force to be 2000 the engine force must be 3000 so that 3000-1000=2000N. and if the engine force would have been 1000 then the resultant force would be zero and the car would have moved with a constant speed and acceleration would not have been possible!!!

 

[falcon678]

I just studied Newton's third law. It says that there is an equal and opposite reaction to every action so won't that reaction cancel out the action causing the object to stay in rest???

no man...itz actualy tht the action n reaction takes place in OPPOSITE bodies.....for example if i extert a force of 2 N on the wall...the wall wil also exert force of 2 N on me....not tht i wil exert a force of -2N on wall along sides 2 N....!

 

[falcon678]

no it is not good the force applied due to engine is 3000N. from the equation F=ma, we get the resultant force and for the resultant force to be 2000 the engine force must be 3000 so that 3000-1000=2000N. and if the engine force would have been 1000 then the resultant force would be zero and the car would have moved with a constant speed and acceleration would not have been possible!!!

dude can u explain tht furthr.....i think tht is wrong.....

 

[falcon678]

F=ma, so the resultant force would be 2x1000= 2000N.
And if the car is accelerating then the resistant force is cut out. 2000N-1000N= 1000N. That is the force applied by engine.
Am I correct?

i gues u r..!

 

[Suchal Riaz]

I just studied Newton's third law. It says that there is an equal and opposite reaction to every action so won't that reaction cancel out the action causing the object to stay in rest???

If someone(not super man) exerts force against wall, it won't move. So where did my force go? actually due to inertia wall will give same force in opposite direction, for example 10N and -10N, so the resultant force is zero and nothing moves.
If you exert force of 10 N on a basket ball it will move so opposite force will not cancel my force as it's inertia is very less for objects with less mass.
We don't need to know much about third law and inertia.
I hope my answer helps.

 

[Suchal Riaz]

no it is not good the force applied due to engine is 3000N. from the equation F=ma, we get the resultant force and for the resultant force to be 2000 the engine force must be 3000 so that 3000-1000=2000N. and if the engine force would have been 1000 then the resultant force would be zero and the car would have moved with a constant speed and acceleration would not have been possible!!!

you are absolutely right.

 

[Suchal Riaz]

dude can u explain tht furthr.....i think tht is wrong.....

resultant force is sum of force.
force of engine is x
force of resistance is -1000N(opposite direction)
resultant force if 2000N
so, x+(-1000)=2000, x=3000N