A skateboarder coasts a distance of 20 meters in 4 seconds. What is the person's speed?

Aboat radioed a distress call to a coast guard station. at the time of the call, a vector a from the station to the boat had a magnitude of 45.0 km and was directed 15.0° east of north. a vector from the station to the point where the boat was later found is = 30.0 km, 15.0° north of east. what are the components of the vector from the point where the distress call was made to point where the boat was found? in other words, what are the components of vector c = b - a?

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value

What is friction? how does it affect the motion of an object?