A level physics multiple choice

Hello there, I am really struggling to get the right answers with the following multiple choice questions!!
If anyone could help me by explaining their thought process on getting the right answer, that would be really helpful

the answers are:
D
D
A

That should really be a 5 mark question and not 1 mark, lol

Nah. 2 at most. It's just (10*1.45)/(1.26) - 10 = r

Wow my method was allot more complicated then yours. I am intrigued as to how you got that equation, I really dislike electricity

1) (10/10+r) = 1.26/1.45
Rearrange for r.

2) Force = Mass*Acceleration. You can find acceleration from v^2 = u^2 + 2as

3) It will take half the time of flight to reach its maximum height.
Use v = u + at for vertical motion. v = 0 at max height. Then use v^2 = u^2 + 2as to find height.

For question 3 can't you just use s=vt-1/2at^2?

You don't have the speed at the beginning. Once you have worked out the original speed, you can also use s = ut + 0.5at^2 [it's + not -, just the acceleration is minus].

As you said before at maximum height v=0 leaving you with s=-1/2at^2. So plugging a=-1.6 it then becomes s=-1/2(-1.6)t^2?

The emf does not change. Voltage is "used up" by a component due to a linear relationship dependant on the percentage of resistance that the component uses. In the original scenario, the switch is open so the only component is the resistor. Therefore, all the emf is used in the resistor and none in the battery due to its internal resistance.

When the switch is opened, current flows. The voltage across the resistor drops, telling you there is an internal resistance as stated. The ratio between the voltage passing through the resistor and total, and between resistor and total are the same. This is to say the following:

Vr/Vt = Rr/Rt

We are given Vr as 1.26.
Vt is equal to the emf, so equal to the voltage across the resistor with no flowing current.
Rr is 10.
Rt is Rr+Ir = 10+Ir

1.26/1.45 = 10/(10+Ir)
10+Ir = (10*1.45)/(1.26)
Ir = (10*1.45)/(1.26) - 10 as given.

I am sorry that I may be a pain in the ....

Your conclusion of
Vr/Vt = Rr/Rt
is a just simple potential divider formula in the disguise.

Yes, but I thought it would be worthwhile explaining why, rather than just saying "Use this cos it's right." oe

I believe that potential divider formula should be well explained in most of the A level physics texts.

If you had referred the following deduction
"Voltage is "used up" by a component due to a linear relationship dependant on the percentage of resistance that the component uses."
from the potential divider formula, I believe your argument is more easy to follow. Anyway that is me.

By the way, how does current flows in an open circuit?
"... When the switch is opened, current flows...."