Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.

Rachel,an engineering student,was asked to make a model shaped like a cyclinder with two cones attached at its two ends by using a thin aluminium sheet.The diameter of the model is 3 cm and its length is 12cm.If each cone has a height of 2 cm,find the volume of air contained in the model that Rachel made.(Assume the outer and inner dimensions of the model to be nearly the same).

A trolley of mass 200 kg moves with a uniform speed of 36 km/ h on a frictionless track. A child of mass 20 kg runs on the trolley from one end to the other (10 m away) with a speed of 4 m s^-1 relative to the trolley in a direction opposite to the its motion, and jumps out of the trolley. What is the final speed of the trolley? How much has the trolley moved from the time the child begins to run?

Two waves of wave length 100 and 101 cm produce 20 beats in 6 seconds in air.Find the velocity of sound in air.

If the speed of sound 336m/s in air, then find the shortest length of the one end closed tube that will resonate with a fork of frequency 21oHz.

Two inclined frictioniess tracks, one gradual and the other steep meet at A from where two stones are allowed to slide down from rest, one on each track (Fig. 6.16). Will the stones reach the bottom at the sam time? Will they reach there with the same speed? Explain. Given 0?t = 30°, 0_2 = 60°, and h = 10 m, what are the speeds and times taken by the two stones?

Assume the thermal conductivity of copper is 4 times that of brass.Two rods of copper and brass having the same length and cross section are joined end to end.The free and end of copper is at 0°C and the free end of brass is at 100°C.Calculate the temperature of the junctionof thw two rods at equilibirum.