68) The radius of a wheel is 80 cm and the radius of the axle is 20 cm. The velocity ratio of the wheel and axle is

69) A mild steel rod of 25 mm diameter is subjected to tensile load of 1000 kg. Calculate the stress

70) A car moving at a speed of 25 km/hour is brought to rest in 20 seconds. Find out the distance travelled by the car before coming to halt.

71) One train 60 meters long is running with a speed of 20 km per hour. It passes from a bridge of 90 meters long. What time will be taken by the train to pass from bridge?

72) In the metal conduit system of wiring where there is a zigzag wall protection, the cables can be run by using