a. A car driving in a straight line at 20 m/s.
Explanation:
An object is in a state of equilibrium when no force is acting upon it. There are two types of equilibrium; static equilibrium and dynamic equilibrium.
Static equilibrium is a state when a body is at rest.
Dynamic equilibrium is an equilibrium state when a body is moving at a constant velocity. (Rectilinear Motion).
A car moving in a straight line at 20 m/s has a constant velocity and hence no force is acting on it. So, it is in dynamic equilibrium.
A book sitting on a table without moving is not is dynamic equilibrium but in static equilibrium.
A boy jumping off a diving board in not in equilibrium as gravitational force is acting upon him and he has a changing velocity.
A motorcycle going in a circle at a constant speed has changing velocity because the direction of the motion is constantly changing hence it is not in the state of motion.
Keywords: velocity, force, equilibrium, static equilibrium, dynamic equilibrium
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U have to *modify it to increase its ground clearance*
As the radial distance between two objects increases, the gravitational force which pulls the two towards each other decreases following the inverse square law. This is based on Newton's Law of Universal Gravitation, which as an equation states . If the distance between the two is doubled, the force of gravity is only 1/4 as strong. If it is tripled, it is only 1/9 as strong, and so on.