1. the coefficient of kinetic friction between an object and the surface upon which it is sliding is
0.25. the weight of the object is 20n. what is the force of friction?

Force of friction in the given question is 5 N

Given that;

Coefficient of kinetic friction μ = 0.25

Weight of the object = 20N

Find:

Force of friction

Computation:

Force of friction = Coefficient of kinetic friction μ × Weight of the object

Force of friction = 0.25  ×  20

Force of friction = 5 N

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5 N

Explanation:

Friction force is normal force times coefficient of friction

F = Fn μ

On level ground, normal force equals weight.

Fn = W

Substitute:

F = Wμ

F = (20 N) (0.25)

F = 5 N

28. evolution

29. environment, survive, offspring  

explanation:

3. dark matter

empty space could also be a simple vacuum