Quick Questions (1 Viewer)

[imoO]

Hey guys,

just need a few expainations for questions I don't understand

Question1

Question 2

Question 3

Cheers

 

[raniaaa]

hey question 3 'untouchablecuz' solved for me and this was his working:

http://img194.imageshack.us/img194/4369/projectile.jpg

Originally Posted by untouchablecuz
im an idiot, i didnt root the time

y=-4.9t<SUP>2</SUP>+490

t<SUP>2</SUP>=100

t=10

.'. x=u<SUB>x</SUB>t=10*100=1000m hence B



^ that follows on from the link

 

[untouchablecuz]

Hey guys,

just need a few expainations for questions I don't understand

Question1

Question 2

Question 3

Cheers

1)

back emf is related to law of conservation of energy (due to Lenz's law of the currents running through a coil)

voltage transformation is related to law of conservation of energy (P_IN=P_OUT)

escape velocity, point where |final E_p|=initial E_k - this is essentially related to the law of conservation of energy , where the intial kinetic energy of the object is equal to the final GPE

.'. by process of elimination, the answer is A

2)

F=qvBsin(x)

F is proportional to q and B

.'. A and B are not the answer

now, if we have a velocity vector, it can be broken up into two parts; a vertical component and a horizontal component. we know by the right hand palm rule that if the velocity is parallel to the magnetic field, then the force will be zero. thus, we can deduce that the parallel component of the velocity will have NO effect on the force acting on the particle.

.'. the answer is C

 

[00iCon]

seconded
That's:
1) A
2) C
3) C