• 9702 June 2014 Paper 23 Worked Solutions | A-Level Physics

Paper 23

Question 1

(a)

Underline all base quantities in following list::

ampere             charge              current             mass    second             temperature     weight

(b)

Potential energy E_P stored in stretched wire is given by E_P = ½Cσ²V where C is a constant, σ is strain, V is volume of wire. SІ base units of C:

Base units of σ: no units

Base units of V: m³

Base units of E_p: kgm²s^-2

Base units of C: kgm²s^-2 x m^-3 = kgm^-1s^-2

Question 2

{Detailed explanations for this question is available as Solution 1016 at Physics 9702 Doubts | Help Page 212 - http://physics-ref.blogspot.com/2015/10/physics-9702-doubts-help-page-212.html}

Question 3

{Detailed explanations for this question is available as Solution 608 at Physics 9702 Doubts | Help Page 120 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-120.html}

Question 4

Spring hangs vertically from point P, as shown. Mass M is attached to lower end of spring. Reading x from metre rule is taken, as shown. Fig shows relationship between x and M.

(a)

How apparatus in Fig may be used to determine load on spring at elastic limit:

Small masses can be added to cause the extension. Then, the masses hare removed to see if the spring returns to its original length. This is repeated for larger masses and the maximum mass for which, when the load is removed, the spring does return to its original length, is noted.

(b)

Explain whether Fig suggests that spring obeys Hooke’s law:

Hooke’s law requires the force to be proportional to the extension. The graph shows a straight line, hence the spring obeys Hooke’s law.

(c)

Use Fig to determine spring constant, in Nm^–1, of spring:

Spring constant, k (= gradient) = force / extension

k = (0.42x9.81) / [(30 – 21.2)x10^-2] = 47 (46.8) Nm^-1

Question 5

Explain why the terminal potential difference (p.d.) of a cell with internal resistance may be less than the electromotive force (e.m.f.) of the cell.

Question 6

{Detailed explanations for this question is available as Solution 533 at Physics 9702 Doubts | Help Page 104 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-104.html}