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An object with a mass of #2 kg# is moving at #7 m/s# over a surface with a kinetic friction coefficient of #2 #. How much power will it take to accelerate the object at #8 m/s^2?

Answer 1

Emily Abbate

The power is #=386.4W#

The mass of the object is #m=2kg#

The speed is #u=7ms^-1#

The acceleration is #a=8ms^-2#

The coefficient of kinetic friction is

#mu_k=F_r/N=2#

The normal force is #N=2gN#

The frictional force is #F_r=mu_k xx N=2*2g=4gN#

The force necessary to accelerate the object is #=FN#

The acceleration due to gravity is #g=9.8ms^-2#

According to Newton's Second Law

#F-F_r=ma#

#F=ma+F_r=((2xx8)+(4g))N=55.2N#

The power is

#P=Fxxv=55.2*7=386.4W#

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Answer 2

Benjamin Asiedu

The power required to accelerate the object at 8 m/s^2 is 30 watts.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.