Momentum and GP

http://www.tomred.org/uploads/7/7/8/3/778329/physics_qp_u4a_specimen.pdf

Could someone help me with 3 please and 13?
And for q 21) Why is the rate of change of flux linkage constant?
Doesn't it increase?

Thanks!

hi Zenarthra
for q 21 the answer is C?

Bump

Yes, do you know why?

The induced emf is proportional to the rate of change of flux (tangent of the graph). since there is a change of flux and the rate is a constant (straight line curve ), the induced emf is of a constant value.. thus the horizontal line.

I'm not sure though ;] what do you think?

You may get more chance of a reply if you post the question, rather than a link, and say what help you need.

For question 13)
What would i use to solve it?
For question 3)
Why isnt it the area under the graph, which gives change of momentum?

13. Grav potential difference is work done per kg.
If it's 3 J/kg over 10m and the field is uniform it's 1.5 J/kg over 5m.
You are given the mass in kg so what is the number of joules needed over that 5m?

3. Is the given answer not C?

Ahh yes it is thanks!
I got confused with another question.

Could you take alook at this please?
http://www.thestudentroom.co.uk/showthread.php?t=2666881&p=47402279#post47402279

As a poster in the thread has said, Ln V against t gives a straight line. The maths tells you this. Take logs of both sides of the formula for discharge. You get y = mx +c with negative m.