A charge is distributed uniformly along a long straight wire. The electric field 2 cm from the wire is 36 N/C. The electric field 4 cm from the wire is:

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.

Acircular pipe of 30mm outside diameter is placed in an airstream at 30 c and latm pressure. the air moves in cross flow over the pipe at 20 m/s, while the outer surface of the pipe is maintained at 110 c. what is the drag force exerted on the pipe per unit length? what is the rate of heat transfer from the pipe per unit length?

Avertical steel rod of length 2.0 m and diameter 25 mm is rigidly fixed at its upper end and has a flange at its lower, free, end. what will be the maximum stress produced in the rod when a load of 20 kn is applied, (a) gradually to the lower end, (b) suddenly to the lower end, (c) by a collar falling from a height of 50 mm on to the flange?