An object will only change its motion if a force is directly applied to it. is this a true statement?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?

Humidity is to blame for that muggy, steamy feeling you experience on some hot summer days. what gas in the atmosphere causes humidity? a) oxygen b) hydrogen c) nitrogen d) water vapor