(a) Explain the term work

(b) Draw a diagram of a pulley system with a velocity ratio of 5.

(c) A man pulls up a box of mass 70kg using an inclined plane of effective length 5m onto a platform 2.5m high at uniform speed. If the frictional force between the box and the plane is 100N, draw the diagram of all the forces acting on the box when in motion and calculate the

(i) minimum effort applied in pulling up the box

(ii) velocity ratio of the plane

(iii) mechanical advantage of the plane

(iv) efficiency of the plane

(v) energy lost in the system

(vi) work output of the man

(vii) total power developed by the man given that the time taken to raise the box onto the platform is 50s. (g = 10ms\(^{-2}\)).

(a) Explain the term resonance and give two examples

(b)(i) Describe, with the aid of a labelled diagram, an experiment to show how the frequency of the note emitted by a vibrating string depends on the length of the string.

(ii) State two precautions necessary to obtain an accurate result.

(c) A sonometer wire is plucked and it vibrates emitting a fundamental note. State the effect on the frequency of the note if the

(i) tension in the wire were made nine times as large with no change in the length of the wire;

(ii) length of the wire were doubled with no change in the tension.

(a) Sketch the form of the magnetic flux pattern due to a current flowing

(i) in a long solenoid

(ii) through two long straight parallel wires when the directions of the current are opposite. (Neglect the earth's magnetic field).

(b) Draw a labelled diagram of an electric bell and explain how it works

(c) An electric bell takes a current of 0.2A groin a battery of two dry cells connected in series. Each cell has an e.m.f. of 1.5V and an internal resistance of 1.0\(\Omega\).

(i) Calculate the effective resistance of the bell

(ii) What current would the bells take in the cells were arranged in parallel?

(a) Briefly explain what would happen to a stable element if it is bombarded by \(\alpha\)-particles

(b) Explain how the bombardment of Uranium with neutrons could lead to nuclear fission chain reaction and hence nuclear explosion.

(c) State three characteristics of nuclear activity

(d) State three applications of atomic energy

(e) State two postulates of Bohr's model of the atom and two limitations of such a model