Imagine 3 moving things
1) sports car
2) bunny running after a carrot dangling on the sports car
3) human, running after his runaway bunny
One thing that probably jumps out at you after you visualise this scene, is that all 3 things are travelling at different speed.
speed = velocity
velocity is about HOW FAST something is.
Sports car = VERY FAST velocity
Rabbit = FAST velocity
human = SLOW velocity
Scientists go one step further with knowing the velocity of something, because it can tell you about the amount of kinetic energy of the object!
If the bunny is 0.1Kg heavy, and is running at a speed of 1m/s
it has kinetic energy of 0.05 Joules
What scientists also know from Newton’s first law, is that if the bunny is running on a frictionless surface,
that kinetic energy of 0.05 joules allows the bunny to RUN FOREVER at the speed of 1m/s without stopping or without giving it a choice to stop either.
Taking about no choice of stopping, if you are a spacecraft sent out to to explore Neptune or Jupiter or something, there is a chance that you just keep going and going outwards into space after you pass by Jupiter because you cannot stop at all…
Velocity = speed + direction!
the bunny with 0.05J of energy and the spacecraft will keep going in the SAME DIRECTION, provided nothing happens to the bunny or spacecraft…