The diagram given below shows a ski jump. A skier weighing 60kgf stands at A at the top of ski jump. He moves from A and takes off for his jump at B.

(a) Calculate the change in the gravitational potential energy of the skier between A and B.

(b) If 75% of the energy in part (a) becomes the kinetic energy at B, calculate the speed at which the skier arrives at B.

(Take g = 10 ms^-2).

(c) Does total mechanical energy change during the ski jump?

A block and tackle has two pulleys in each block with the tackle tied to the hook of the lower block and the effort being applied upwards.

(a) Draw a neat diagram to show this arrangement and calculate its mechanical advantage.

(b) If the load moves up by a distance x, by what distance will the free end of the string move up?

Two pendulums C and D are suspended from a wire as shown in the given figure. Pendulum C is made to oscillate by displacing it from it's mean position. It is seen that D also starts oscillating.

(i) Name the type of oscillation, C will execute.

(ii) Name the type of oscillation, D will execute.

(iii) If the length of D is made equal to C, then what difference will you notice in the oscillations of D?

(iv) What is the name of the phenomenon when the length of D is made equal to C?

(a) Students of a class perform an experiment on series and parallel combinations of two resistances R₁ and R₂. Some of the students plotted graph (1) and remaining plotted graph (2). Identify the correct graph and give reason.

A

B

(b) The length of an electric wire is increased by 25%. What is the percentage increase in the resistance and resistivity?

(c) Same current flows through an electric live wire and a bulb filament, but only the filament glows. Give reason.