mass is what makes you and wieght is mass+gravity of the planet you are on.
a car will take longer to break when it is on a slippery road than a dry road because the amount of time is dependant on the friction between the road and tire.
friction is useful to stop a moving object and to stop suddenly.
you caculate speed by: speed =distance/time (/=divided)
the time it takes earthe to orbit the sun once is called a year. it take 365 days for the earth to orbit the sun once. the earth spins on its axis once every 24 hours. the time it takes to spin on its axis is the lenght of that planets day.