Is it possible that the resultant of two vectors a smaller than the smaller of two vectors if so under what condition

When someone slams her books on a table the kinect energy is transferred into vibrations that travel to your ears as sound waves which statement describes the movement of those waves

When many atoms are split in a chain reaction, a large explosion occurs. this is an example of what type of energy conservation

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?