5. A battery of emf E = 12.5 V is connected across a 4m long uniform wire having resistance 40/m. Two cell of small EMFS =2V and 2 = 4V having internal resistance 202 and 602 respectively are connected as shown in the figure. If galvanometer shows no deflection at the point N, the distance of point N (in m) from the point A is equal to : Eo R = 40 ww 6. N A B 1 r1 2 r2 If the block shown in figure is displaced slightly and released, find the time period of oscillations Pm of the block is found to be 2 Find P. K 2K 000000000 T +0000000E K 7. A boat travel, between two points A and B on the opposite banks of a river (figure), always following the line AB. The distance S between points A and B is 240 m. The velocity of the river flow vr 22 m/s is constant over the entire width of the river. The line AB makes an = 45 with the direction of the current. The boat moves to cover the distance AB and back in a time t = 23 min. The angle remains the same during the passage from A to B and from B to A. With what velocity u, should the boat travel? B S B 8. A At an instant t = 0, Block A of mass 1 kg is moving with speed 8 m/s towards right on rough surface of block B of mass 3 kg. Block B, which is placed on smooth horizontal surface is moving with speed 4 m/s towards right at same instant (t = 0). The net work done against the frictional force in long time is (block A will not fall from block B) A B 8m/s 4m/s