How long must a simple pendulum be if it is to make exactly one swing per second? (that is, one complete vibration takes exactly 2.0 s.)

Oscillation is a type of periodic motion which repeats itself to and from about a point which is called mean position. The period of a Pendulum can be described as a ratio between the length and gravity as,

Here,

L = length

g = Gravity

If we rearrange  to find the length we have that,

Our period is 2s and the gravity is 9.8m/s^2, then,

The simple required length of the pendulum must be 0.9929m

the device is called “ rocket engine”

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.