Physics: Post your doubts here!

[princess Anu]

why not C? :/ increasingthe resistance of resistor will decrease the Potential difference across the plates & hence the Electric field.. no?:/

 

[princess Anu]

whats the diff b/w A & B? :s

 

[princess Anu]

why not D?

 

[princess Anu]

.

 

[qwertypoiu]

.

Positive charge is induced on the bottom plate by the top one since they are placed close to one another.

 

[qwertypoiu]

why not D?

Height does not increase uniformly as the ball goes up, since s = ut + 1/2*a*t^2.
Thus neither does the gpe.

The line isnt straight when it goes up as you can see.

 

[princess Anu]

Positive charge is induced on the bottom plate by the top one since they are placed close to one another.

but the bottom plate is earthed so it should possess no charge nd shud be neutral, no?

 

[ashcull14]

f=ma since mass is constant F is proportional to acceleration, & since acc is uniform hence Force is uniform too!

ans is B..thts wht im asking

 

[qwertypoiu]

but the bottom plate is earthed so it should possess no charge nd shud be neutral, no?

When the negatively charged plate is brought close to the initially neutral plate, the electrons in the bottom plate are repelled away and move into the earth, since a wire is connected so the electrons are able to flow away. This makes the bottom plate become overall positively charged, since there are more protons than electrons.

 

[qwertypoiu]

ans is B..thts wht im asking

"accelerate uniformly" means constant acceleration.
F = ma
Since the mass is constant and acceleration is constant, the resultant force F must be constant too.

 

[nehaoscar]

Doesn't the horizontal component of velocity always remain the same? (projectiles chapter)
Then how is it D? :/

 

[nehaoscar]

How to do this one??

 

[qwertypoiu]

View attachment 54017
Doesn't the horizontal component of velocity always remain the same? (projectiles chapter)
Then how is it D? :/

That is when air resistance is ignored. However in this case air resistasnce is not ignored, so you'd expect the horizontal component to decrease to zero.

 

[nehaoscar]

I'm getting A ... the load is in kg and the extension should be in metres
force = area under graph
= trapezium rule = .5 x (3.8+2) x (10 x 10^-3)
This gives 0.028 and not 0.28 ... but the answer is C ...... how??

 

[nehaoscar]

That is when air resistance is ignored. However in this case air resistasnce is not ignored, so you'd expect the horizontal component to decrease to zero.

So when there is no air resistance, horizontal component will always decrease?

 

[qwertypoiu]

View attachment 54018
How to do this one??

C??

 

[nehaoscar]

 

[qwertypoiu]

So when there is no air resistance, horizontal component will always decrease?

When there is no air resistance, horizontal component always remains the same.
Where there is air resistance, horizontal component decreases.

 

[nehaoscar]

C??

Nope ... it's B

 

[qwertypoiu]

View attachment 54020

C?