2006 - JAMB Physics Past Questions and Answers - page 1

For the uniform cube 10cm volume = 10 x 10 x 10 = 10³ cm³

Mass = 700g

∴ density = (Mass)/Volume = (700)/100 = 0.7gcm^-3

since the density is less than the density of water, the cube will float

R.D = (density of the subs)/density of water

19.2 =(P)/10³; ∴P = 19.2 X 10³

But Vol. = (Mass)/density = (2.4)/19.2 x 10³

= 1.25 x 10^-4 M³

The thermometric property of a constant volume thermometer is change in pressure with temperature

Power of heater = lvt = 2 x 240 x t

heat required to boil the water = Mct = 2.5 x 4.2 x 10³ x (100.52) = 2.5 x 4. 2 x 10³ x 48

2 x 240 x t = 2.5 x 4.2 x 10³ x 48

∴ t = (2.5 x 4.2 x 10³ x 48)/2 x 240

= 1050s or 1.05 x 10³s

p is the time rate of expending energy. for electrical energy, P = IV; 1²R or (V)/R. For a cell of constant e.m.f (voltage) maintaining constant current(1) through the circuit, P α R; OR (1)/R.

Again for maxi. power,p α R

And with respect to the opinion, maxi power would be transferred when R>r:not necessarily R = 2r