Physics need help

[JaWaD]

MayJune 08 physics p1
q9 , why can't B be right
q37 , why the reading does not go to zero
http://www.xtremepapers.net/CIE/Cambrid ... 8_qp_1.pdf
please anyone explain

 

[Zishi]

Q9- Because all the kinetic energy isn't converted to heat energy. Heat energy is just produced WITH the kinetic energy.
Q37- Because there's another resistor present, too!

 

[Angraiz]

For 9: The ball will first have potential energy. It will begin to fall, the potential energy changing to kinetic energy(because it is moving) and heat energy(loss due to friction) till it goes to the first stopping point. Speed will be zero, kinetic energy will be converted into potential energy and heat energy because there is still heat loss due to friction.

For 37: The resistance won't decrease to 0, therefore voltage won't decrease to 0.


Zishi, for 37, it is asking for potential difference across thermistor, you don't have to consider the second resistor.

 

[Zishi]

For 9: The ball will first have potential energy. It will begin to fall, the potential energy changing to kinetic energy(because it is moving) and heat energy(loss due to friction) till it goes to the first stopping point. Speed will be zero, kinetic energy will be converted into potential energy and heat energy because there is still heat loss due to friction.

For 37: The resistance won't decrease to 0, therefore voltage won't decrease to 0.


Zishi, for 37, it is asking for potential difference across thermistor, you don't have to consider the second resistor.

Oh! Thanks for the correction, man!