3 years ago

Which of the following is a chemical change?

1 answer:

3 0

a). Water is still H₂O after it freezes.

b). Ice is still H₂O after it melts.

c). Wire is still Cu when it's bent.

d). Paper combines with the O₂ in the air, and turns into
a lot of new compounds when it burns.

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A 6.0-kg box slides down an inclined plane that makes an angle of 39° with the horizontal. If the coefficient of kinetic frictio

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Answer:

a. $3.1 m/s^2$

Explanation:

The equation of the forces along the directions parallel and perpendicular to the slope are:

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$mg sin \theta - \mu_k R = ma$

where :

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g = 9.8 m/s^2 the acceleration of gravity

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R is the normal reaction

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From the 2nd equation, we get an expression for the reaction force:

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$mg sin \theta - \mu_k mg cos \theta = ma$

Solving for a,

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