physixx mcqs

[hassam]

i neva undrstood this

 

[Zenzenzen]

This used to confuse the hell out of me too! What you have to do is think of the dots as stuck in a vertical plane. The dots cannot move in a horizontal direction, only a vertical one. THE DOTS CANNOT MOVE. ONLY THE WAVE.

So for example since the wave is moving towards the right, dot A will be going downwards.
The answer to this question would be C, as it is moving upwards with maximum speed.

D will only move slightly upwards.

Hope you understood that ^_^

 

[hassam]

 

[sparten]

B

 

[hassam]

cn u xplain

 

[sparten]

well its simple tenergy possesed in this case is due to the motion.....
the masses experiences velocity v due to difference btw the magnitude of both mases
enery posessed due to motion is 1/2 mv^2
m=(m1-m2)

 

[hassam]

:Search: :Search: :Search:

 

[hassam]

is the half life UNCErTAIN cos of these FLUCTUATIONS

 

[Amna]

but isn't that the energy possessed by the system? the question asks for the energy provided by the motor...

 

[sparten]

enery provided by motor is used in making mases move...
energy provided =energy used in producing v

 

[sparten]

is the half life UNCErTAIN cos of these FLUCTUATIONS

A

 

[xHazeMx]

answer is B

 

[jumana94]

Dude Sparten your answer is wrong! its D not B, hassam...
Reread the question carefully, he is asking for the rate at which energy is provided. Energy over time is Power..
Another formula for power is Force*Speed... force =ma
acceleration here is g... So mgv....but we need the change in mass, so the answer is (m1-m2)gv....which is D
if u want to make sure about the answer, check out nov2010 varient 1, see the marksceme

 

[xHazeMx]

Dude Sparten your answer is wrong! its D not B, hassam...
Reread the question carefully, he is asking for the rate at which energy is provided. Energy over time is Power..
Another formula for power is Force*Speed... force =ma
acceleration here is g... So mgv....but we need the change in mass, so the answer is (m1-m2)gv....which is D
if u want to make sure about the answer, check out nov2010 varient 1, see the marksceme

100 % correct

 

[girlscampisra]

another way is just to check homegenity of equations

 

[xHazeMx]

that's correct too ..

 

[hassam]

y we need difference in mass........it just doesnt sticks in ma mind

 

[xHazeMx]

y we need difference in mass........it just doesnt sticks in ma mind

because the two masses are moving in different direction so u will have to find the difference in weights, just like acceleration and friction

 

[sparten]

Dude Sparten your answer is wrong! its D not B, hassam...
Reread the question carefully, he is asking for the rate at which energy is provided. Energy over time is Power..
Another formula for power is Force*Speed... force =ma
acceleration here is g... So mgv....but we need the change in mass, so the answer is (m1-m2)gv....which is D
if u want to make sure about the answer, check out nov2010 varient 1, see the marksceme

oo yeah sorry i just misread the question...

 

[hassam]