Question

A 54-kg bungee jumper has fallen far enough that her bungee cord is beginning to stretch and resist her downward motion. Find the force (magnitude and direction) exerted on her by the bungee cord at an instant when her downward acceleration has a magnitude of 8.3 m/s2. Ignore the effects of air resistance.

Answer 1

91.8 N

Step-by-step explanation:

For the second law of Newton, the resultant force (F) is the mass(m) multiplied by the acceleration (a). Two forces are acting: the weight and the force exerted by the bungee cord (Fb). They are at same directions but in different ways, so the resultant force will be the difference between them (Fb is in a positive way):

Fb - m*g = m*a

The acceleration is on downward, so it is -8.3 m/s²

Fb - 54*10 = 54*(-8.3)

Fb = -448.2 + 540

Fb = 91.8 N