Answer:
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north).
Explanation:
Answer: The weight of a 72.0 kg astronaut on the Moon is 117.36 N.
Explanation:
Mass of the astronaut on the moon , m= 72 kg
Acceleration due to gravity on moon,g = 1.63 
According to Newton second law of motion: F = ma
This will changes to = Weight = mass × g

The weight of a 72.0 kg astronaut on the Moon is 117.36 N.
Yes, but it's a null vector .So,no vector can have a component at right angle to itself unless it is a zero vector.
Answer:
a.
Explanation:
a
The property of air mass include
1) it must be large.
2) it must have relatively uniform properties.
3)it must travel as a recognizable entity.
It must have a warm front at its leading edge, is not necessarily a property of an air mass because Not all air masses have a warm front at their leading edge. There are five types of air masses and different types of the front can be developed.