Two girls, each of weight 400 N climb up a rope through a height of 8 m. We name one of the girls A and the other B. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?

Two children A and B each weigh 20 kg climb a rope up a height of 10 m. The child A takes 10 s, and child B take 20s, to climb. Out of these two children, who has more power? Compare their powers.

Two children A and B each weigh 20 kg climb a rope up a height of 10 m. The child A takes 10 s, and child B take 20s, to climb. State whether the work performed by both the children is equal or different.

As shown in the given figure. the two sides of a step ladder BA and CA are 1.6 m long and hinged at A.A rope DE, 0.5 m is tied half way up. A weight 40 kg is suspended from a point F, 1,2 m from B along the ladder BA. Assuming the floor to be frictionless and neglecting the weight of the ladder, find the tension in te rope and forces exerted by the floor on the ladder. (Take g = 9.8 ms^-2 ) (Hint: consider the equilibrium of each side of the ladder separately).

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h^-1 in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m s^-2 . If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them ?

A solenoid 60 cm long and of radius 4.0 cm has 3 layers of windings of 300 turns each. A 2.0 cm long wire of mass 2.5 g lies inside the solenoid (near its centre) normal to its axis, both the wire and the axis of the solenoid are in the horizontal plane. The wire is connected through two leads parallel to the axis of the solenoid to an external battery which supplies a current of 6.0 A in the wire. What value of current (with appropriate sense of circulation) in the windings of the solenoid can support the weight of the wire? g = 9.8 m s^-2 .

Observe the histogram (fig.) and answer the question given below: (i) What information is being given by the histogram? (ii) Which group contains maximum girls. (iii) How many girls have height 145 cms. and more? (iv) If we divide the girls into the following three categories, how many would there be in each? 150 cm and more - Group A 140 cm to less than 150 cm - Group B Less than 140 cm - Group C

• Take three iron nails and clean them by rubbing with sand paper. • Take two test tubes marked as (A) and (B). In each test | tube, take about 10 ml copper sulphate solution. • Tie two iron nails with a thread and immerse them 'carefully in the copper sulphate solution in test tube B for about 20 minutes [Fig. (a)]. Keep one iron nail aside for comparison. • After 20 minutes, take out the iron nails from the copper sulphate solution. • Compare the intensity of the blue colour of copper sulphate solutions in test tubes (A) and (B) (Fig. (b)]. Also, compare the colour of the iron nails dipped in the copper sulphate solution with the one kept aside [Fig. - (b)]. On the basis of activity , give the answers of th following questions : What is the colour of copper sulphat solution in test tube A ?