3. The change in altitude of an object falling under gravity is determined by finding the product of -9.75 and the square of the time of the fall, then dividing by 2. Write an equation for the change in altitude, then determine the change in altitude in meters of an object that has fallen for 4 seconds. Recall: Product refers to multiplication.

12000j is work done

a skateboard rolling across the street - apex

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