K.C.S.E Physics Q & A - MODEL 2016PP2QN18

K.C.S.E Physics Q & A - MODEL 2016PP2QN18

​(a)State one factor that affects the speed of sound in a solid.
b)An observer stands half-way between two vertical cliffs that are L metres apart.He strikes a gong and measures the time interval, t, between the
echoes heard from the two cliffs. He moves a further 10m and again strikes the gong and measures the time interval between the echoes. The process is repeated several times. The graph in Figure 13 shows the relation between the time interval, t and the distance, x from the centre.
(i)From the graph, determine the value of x for which the time interval was 0.55.

​(ii)Given that t = 4x/v where v is the speed of sound in air, determine the value of v from the graph.
(iii)If the maximum time measured by the observer was t=4.7s, determine the distance L between the cliffs.
(c)A search boat uses a signal of frequency 6.0 x 104 Hz to detect a sunken ship directly below. Two reflected signals are received; one after 0.1 seconds from sunken boat and the other after 0.14 seconds from the sea bed. If the sea bed is 98 m below the boat, determine:-
(i)The speed of the signal in water. 
You may use the value of v from (ii) above.
(ii)The depth of the sunken ship below the boat

answers

​(a)Temperature
Density
(b)(i)47 metres
(ii)

​(iii)Distance = speed x time
 2D = distance to and from the cliff
 2D = 340.715 x 4.7
 D = 800.68 metres
(c)(i)Distance moved by sound from sea bed = 98 x 2 m
 V = (98 x 2)0.14
 = 1400 m/s
(ii) Distance = v x t
 = 1400 x 0.10/2
 = 70 m