You are to choose five out of the first ten questions.
(1)A fruit from a tree of mass 2kg is 5m above the ground.Calculate the Potential Energy of the fruit if it has fallen 3m from the tree.
(2)An object of mass50kg is placed on aninclined plane at 30degrees to the horizontal.The height of the inclined plane is 250cm and its length is 500cm.What work is done in moving the object down theplane?(Take g=10m/s).
(3)Draw a labelled diagram of a vacuum flask.Explain how its construction minimizes heat with the surrounding.
(4)The length of a side of a metallic cube at 20degrees centigrade is 5cm.Given that the linear expansivity ofthe metal is 4*10^-5,find the volume of the cube at 120 degrees centigrade
(4b)Define the term”cubic expansivity”
(5)What is meant by a dielectric substance?
(5b)List the factors which determine the capacitance of a parallel plate capacitor and state the effect each of them has on capacitance?
(6)Distinguish between stress and strain as used in elasticity
(6b)When a force of 40N is applied to the free end of an elastic cord,an extension of 5cm is produced in the cord.Calculate the work done on the cord.
(7)A stone is projected horizontally from the top of a tower with a speed of 5m/s.It lands on the ground level at a horizontal distance of 20m from the foot of the tower.
Calculate the height of the tower(g=10m/s)
(8b)Draw and label an electrolysis cell
(9)A capacitor of capacitance 25micro-farad is connected to an a.c power source of 200Hz.Calculate the reactance of the capacitor.
(10)A half-life of a radioactive source is 1 minute.If the ratemeter connected to the source registers 200micro-ampere at a given time,what would be its reading after 3 minutes?
(1b)An electric pump whose efficiency is 75% raises water to a height of 20cm.If water is delivered at the rate of 450dm3 per minute,what is the power rating of the pumb?(Mass of 1dm3 of water=1kg).
(1c)In what circumstances is a force said to do work?
(1cii)How is work done measured
(1d)Briefly explain the conversion of mechanical energy in a pendulum bob
(2)Sketch the graph of relation btw the extension of a spiralspring and the load attached to it when it is gradually loaded up the elastic limit.
(2b)What is the physical significance of the area under the graph?
(2c)A spiral spring is 20cm long when at 10N.What is the length of the spring at 2N provided hooke’s law is obeyed.
(2d)State Hooke’s law of elasticity,thus,prove that F=ke.
(3)State the pressure law.
(3b)Explain how the following will affect the given mass of a substance.
(3d)A given mass of gas at 303K is trapped in a tube of volume V.Calculate the temparature of the gas when the volume is reduced to two-thirds of its original value by applying pressure twice the original value?