A 0.44-kg cord is stretched between two supports, 8.1 m apart. When one support is struck by a hammer, a transverse wave travels down the cord and reaches the other support in 0.82 s. What is the tension in the cord? (Express your answer to two significant figures and include the appropriate units.

Answer: 9.8N

Explanation: The velocity of a sound wave (v), tension on the string (T) and mass per unit length (u) are all related by the formulae below

T = v² * u

Where T is tension in Newton (N), v is velocity of sound waves in meter per seconds (m/s) and u is mass per unit length in kilogram per meter (kg/m)

u = mass of chord / length of chord

u = 0.44 / 8.1

u = 0.1 kg/m

Velocity of sound waves (v) = length of chord / time taken for wave to travel

v = 8.1 / 0.82 = 9.9m/s

Tension is calculated below using the formula

T = v² * u

T = (9.9) ² x 0.1

T = 9.8N