Answer:
When air resistance equals the weight of an object, the object has reached free fall.
Explanation:
- When an object has only force acting on it as gravity then, it experiences free fall.
- During free fall all the forces except gravity is balanced by one another.
- In the question, object's weight is balanced by air resistance so it is in the state of free fall.
- At the null point of free fall, object experiences weightlessness i.e. it feels like object is not attracted by any force.
Answer:
A star with 15 solar masses is too big to be a main-sequence star.
Earth's magnetic field is the force acting on the compass needle to cause it to point northeast.
Explanation:
Orbital speed= 2pi x radius / time period
=2pi x 1.5x10^11 / 365.25
=2.58x10^9m/day
Answer: A, C, E
Explanation:
Gamma rays, Microwaves, and Radio waves
