Physics: Post your doubts here!

[nehaoscar]

How???

 

[Ahmed Aqdam]

View attachment 54681
Why C?

As percentage uncertainty is same for all values, the actual uncertainty will be least when θ is least.
Percentage uncertainty= Actual uncertainty/Value*100 so if actual uncertainty is less than value should also be less.

 

[nehaoscar]

Why C.. why not B?

 

[nehaoscar]

Why C ?? please explain!

 

[Boss201]

A car is travelling with uniform acceleration along a straight road. The road has marker posts every 100m. When the car passes one post , it has a speed of 10m/s and , when it passes the next one , its speed is 20m/s

What is the car acceleration ?
A.0.6m/s^2
B.1.5m/s^2
C.2.5m/s^2
D.6.0m/s^2

(from marking scheme answer is (B:1.5m/s^2)[June 2004 paper 1 number 7]

 

[nehaoscar]

A car is travelling with uniform acceleration along a straight road. The road has marker posts every 100m. When the car passes one post , it has a speed of 10m/s and , when it passes the next one , its speed is 20m/s

What is the car acceleration ?
A.0.6m/s^2
B.1.5m/s^2
C.2.5m/s^2
D.6.0m/s^2

(from marking scheme answer is (B:1.5m/s^2)[June 2004 paper 1 number 7]

u = 10 , v = 20 , s = 100
using v^2 = u^2 + 2as
a = 1.5

 

[Boss201]

In a simple electrical circuit , the current in a resistor is measured as (2.50 ± 0.05) mA. The resistor is marked as having a value of (4.7 Ω ± 2%).

If these values were used to calculate power dissipated in the resistor , what would be the percentage uncertainty in the value obtained ?

A.2%
B.4%
C.6%
D.8%

From marking scheme (Ans :C 6%)[Jun 2004 paper 1 number 6]

 

[Boss201]

u = 10 , v = 20 , s = 100
using v^2 = u^2 + 2as
a = 1.5

Thanks

 

[Sarosh Jameel]

PLZ HELP !

 

[nehaoscar]

Why cant't A be in equilibrium??

 

[eliyeap]

View attachment 54688
Why cant't A be in equilibrium??

For an object in equilibrium, the forces acting on it has to have a concurrent point which means they have to have a common point of intersection. If you extend the forces they should intersect at a common point. For A there is no concurrent point

 

[eliyeap]

PLZ HELP !

Is it C?

 

[eliyeap]

In a simple electrical circuit , the current in a resistor is measured as (2.50 ± 0.05) mA. The resistor is marked as having a value of (4.7 Ω ± 2%).

If these values were used to calculate power dissipated in the resistor , what would be the percentage uncertainty in the value obtained ?

A.2%
B.4%
C.6%
D.8%

From marking scheme (Ans :C 6%)[Jun 2004 paper 1 number 6]

Percentage uncertainty of current= 0.05/2.5 * 100=2%
P= (I^2)R
Percentage uncertainty of P= 2(2)+2=6%

 

[nehaoscar]

How D??

 

[nehaoscar]

Why not C??

 

[nehaoscar]

How??

 

[nehaoscar]

Why not B??

 

[nehaoscar]

Someone please explain why C??

 

[Ahmed Aqdam]

View attachment 54690
How D??

Area is reduced four times so so length must increase four times as volume remains same.
Hence resistance will be 0.2*4*4=3.2

 

[Mahnoorfatima]

Just asking, How do you guys post the screenshot thingy? I don't usually get answers if I post the whole paper and ask for a certain question.