Applied Mechanics and Graphic Statics
The characteristic of a couple is:

A couple can be never the balanced by a single force
All listed here
Algebraic sum of moments of forces, constituting a couple, about any point, is same
Algebraic sum of forces, constituting a couple is zero

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Applied Mechanics and Graphic Statics
A ball which is thrown upwards, returns to the ground describing a parabolic path during its flight

Vertical component of velocity remains constant
Horizontal component of velocity remains constant
Speed of the ball remains constant
Kinetic energy of the ball remains constant

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