Asimple pendulum is made from a 0.75-m-long string and a small ball attached to its free end. the ball is pulled to one side through a small angle and then released from rest. after the ball is released, how much time elapses before it attains its greatest speed?

It takes 0.43 seconds before the pendulum attains the maxium speed.

Explanation:

L= 0.75m

g= 9.8 m/s²

T= 2π * √(L/g)

T=1.73 sec

T(vmax) = T/4

T(vmax) = 0.43 sec

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me