cart is moving on a track in the positive x-direction. A force acting parallel to x-axis is excreted on the chart. The chart shows the net force excreted on the chart as a function of displacement. As the cart travels from x=0m to x=4m, what is the net change in kinetic energy of the cart

d) physical means can be used to separate the components of air.

the closer the planet is to the sun, the larger the gravity

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.

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