A 1.0 kg mass hangs at the end of a strong, massless cord attached to a 2.0-kg mass. The 2.0-kg mass hangs at the end of another strong, massless cord. A force applied to the "upper" cord accelerates the system upward at 10 m/s². Assuming that the acceleration of gravity is 10 m/s², the tension in the lower cord is A) 20 N. B) 30 N. C) 40 N. D) 60 N.

Question

Quizplus · Accepted Answer

The tension in the lower cord is equal to the force required to accelerate the 1.0 kg mass upward at 10 m/s^2 plus the force of gravity on the mass. The force of gravity is $1.0 \, \text{kg} \times 10 \, \text{m/s}^2 = 10 \, \text{N}$, and the force required for the acceleration is $1.0 \, \text{kg} \times 10 \, \text{m/s}^2 = 10 \, \text{N}$. Adding these together gives $10 \, \text{N} + 10 \, \text{N} = 20 \, \text{N}$.

A 10 Kg Mass Hangs at the End of a Strong