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# KNEC KCSE Physics Paper 3 – 2014 KCSE COMA Joint Exam

Contents

## KNEC KCSE Physics Paper 3 – 2014 KCSE COMA Joint Exam

### 2014 KCSE COMA Joint Exam

#### Physics Paper 3

1.

QUESTION ONE
You are provided with the following; -A 400ml glass beaker
– A Bunsen burner
– A thermometer
– A stop watch
– A tripod stand and a measuring cylinder 100ml – A wire gauze
– A source of heat.
Set up the apparatus as shown in the diagram below.

Measure 100cm3 of water and pour it into the beaker. Take the initial temperature of the water.
T0…………………………………………………………………………… (1mk).
Now heat the water to a temperature of 90 oC. Switch off the gas tap and place a thermometer into the beaker and start the stop watch when the temperature is 65C. Take the temperature T oC of water every two minutes.

Record your results in the table below.

(7mks)
(i) Plot a graph of Log (T – TO) against Time (t). (5mks)

(ii) Find the value K of log(T – TO) when t = 0 (2mks)

8 marks

2.

This question has two parts A and B. answer both parts.
PART A
You are provided with the following:

– A meter rule
– Two identical 100g masses
– About 200ml of liquid L in 250ml beaker

– Stand with clamps
– Tissue paper.
Proceed as follows:
(a) Using a stand and one piece of thread, suspend the metre rule in air such that it balances horizontally.
Record the position of the centre of gravity. G.
G = ________________________ mm
NOTE: The metre rule should remain suspended at this point through out the experiment.
(b) Set up the apparatus as in figure 2 below.

Suspend the mass A at a distance x = 50mm. adjust the position of mass B until it balances mass A
immersed in liquid L.
Record the distance d, of mass B from the pivot.
Repeat the same process for other values of x in table 2 below and complete the table.

(3 mks)

(c) Plot a graph of d (y axis) against x. (5mks)

(d) Determine the slope, S of the graph. (2mks) ………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
……………………………………………………………………………………..………………………
(e) Given S = F/ W , where F is the apparent weight of object A in the liquid L and W is the actual weight of A, find:-
(i) The value of F. (2mks) ………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
(ii) The upthrust, U (3mks) ………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
PART B
You are provided with the following:

– A concave mirror with holder
– A screen
– A meter rule
– A candle
– A match box (to be shared)
Proceed as follow:
(f) Set up the apparatus as in figure 3 below.

(g) Put the oblect at a distance u = 30cm from the mirror. Adjust the position of the screen until a sharp image is formed on the screen. Record the distance V.

(h) Repeat procedure (b) above for the distance u = 40cm and record the new distance V. complete the table 3 below.

(2mks)
(i) Given f = V/(m +l) , calculate the values of f hence determine the average value fav: (3mks) ………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………

22 marks