Name one use of 'LASER' in each of the following areas:

(a) communication;

(b) medicine;

(c) security

The accelerating potential in a cathode ray oscilloscope is 2.5 kV. Calculate the maximum speed of the accelerated electrons. [ e = 1.6 x 10\(^{-19}\) C; Me = 9.1 x 10\(^{-31}\) kg]

Write down the name of:

(a) two particles used in explaining the wave nature of matter;

(b) one device whose invention is based on the wave nature of matter.

(a) what is Brownian motion?

(b) State the two inferences that can be drawn from Brownian motion experiment.

(a) State the triangle law of vector addition.

(b) Name the four physical quantities that are associated with the equationq of linear motion.

(c) Using the same set of axes, sketch and label two graphs to illustrate the variation of potential energy and kinetic energy with time for a body in simple harmonic motion.

(d)

A light spiral spring of force constant K lies on a horizontal frictionless surface and has one end fixed to a vertical wall. A block P of mass 2.0 kg placed against the free end of the spring is pushed a distance 5 cm towards the wall with 10J of energy as illustrated in the diagram above. The block is released and after 0.25s, it collides inelastically with a stationary block Q of mass 4.0 kg. Calculate the:

(i) value of k;

(ii) force used to compress the spring;

(iii) acceleration of the block p after release;

(iv) common speed after collision of the blocks.