Please mark me brainliest!
1. Nope. If the net forces are zero, it means that the object is at an equilibrium state (may be static of dynamic), and thus implies the forces cancel or balance each other out.
2. It's actually air resistance. I suggest you read about Aristotle's and Galileo's experiment about the topic (gravity).
3. Ain't sure with this one. ^^;
4. Recall that gravitational force can be measure using the formula:
F = G*m1*m2 / r^2
where m1 and m2 are the masses of the objects, and r is the distance between them.
Thus, F is largest when the objects are very massive, and they are close with each other. And therefore, it's "two stars very close to each other".
5. I think it's the rolling friction, because there would be less contact between the tracks and the wheels of the train.
6. It's "a cruise ship travels west at a constant speed". Note in order to have a constant velocity, you must have both magnitude and direction as constant.
7. It's the size of the object. Note that distance, velocity and acceleration are the essential concepts of kinematics.
