physics m/j 2002 confusions

[izzahzainab]

im having problem understanding the concept behind these MCQ's.

5. why is it not B ????
15. problem :0
35. i got this right thinking "resistance decreases-potential DIFFERENCE decreases"........but why could it not have been "resistance decreases-current inreases-according to ohms law, p.d increases" :0

 

[CaptainDanger]

5. Its not B because Velocity is acting at a tangent to the circle not force.... Acceleration and force are towards the centre of circle....

15. Its easy

See you can solve it using ratio

From diagram
25 cm represents 120°C

So
1cm ----> 120/25
Questions is asking at 15 cm

So

15cm----- 15 into 120/25 = 72°C

You have to tell the temperature from -10°C so answer is 72°C -10°C = 62°C

35. See both the resistors are connected in series so Current is constant.... We know that V=IR keeping current constant V becomes directly proportional to R so when R decreases V decreases too... But not to zero...
While in Ohm's Law temperature and other conditions needs to be constant.... Here in question thermistor us heated...

 

[izzahzainab]

thanku!

 

[CaptainDanger]

You are welcome....