Answer
Hi,
The forces are; weight (gravity), Normal/centripetal force and friction. Force due to gravity is constant where as friction and centripetal are not.
Explanation
Weight is constant, given by the force of gravity on the object. The centripetal force is a function of the angles occurring between the velocity vector and the weight vector that is at right angle with the perpendicular line drawn from the surface. Friction is a function of the centripetal force thus it also varies.
Hope this helps!
The temperature of the air above it
Answer:

Explanation:
Given data
time=0.530 h
Average velocity Vavg=19.0 km/s
To find
Displacement Δx
Solution
The Formula for average velocity is given as

Answer:
The answer is D.
Explanation:
Average speed involve just distance and time but average velocity includes displacement and time.
(Correct me if I am wrong)
Answer: because they have equal numbers of protons
Explanation: Atoms are electrically neutral because they have equal numbers of protons (positively charged) and electrons (negatively charged). If an atom gains or loses one or more electrons, it becomes an ion