A child on a skateboard is traveling at a velocity of 8 m/s down a hill. At the bottom of the hill, he slows down and comes to a stop in 4 seconds. Calculate the sled's deceleration. Depict which equation to use

a=vf-vi/t
t=vf-vi/a
vf=(a•t)+vi

What is work? how much work is done to move an object 0 meters?

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost

Scientists follow specific processes in order to determine valid explanations and conclusions from observations. david observed strange lights in the sky above his home outside of roswell, new mexico. the only explanation that makes sense to him is that there are ufos in the area. what should david do next to verify his explanation?