1)
car a has a mass of 1,000 kg and is traveling 60 km/hr. car b has a mass of 2,000 kg and is traveling 30 km/hr. compare the kinetic energy of car a with that of car b?
a) equal
b) half as much
c) twice as much
d) four times as much

The kinetic energy of car A is  twice as much as car B. Option C is correct.  

Kinetic energy of car A:    

Since, m =1000kg  

         Va =16.66 m/s  

Thus,

KEa = (1000 kg x 277.556m²/s²)/2  

KEa = 138 777.8 J

Kinetic energy of Car B:

Since ,

m = 2000 kg  

Vb = 8.33 m/s  

Thus,  

KEb =(2000 kg  x 69.39 m²/s²)/ 2  

KEb = 69 388.9 J

Now compare KEa with KEb  

KEa /KEb   = 138 777.8 J/ 69 388.9  

KEa /KEb   = 2

Therefore, the kinetic energy of car A is  twice as much as car B.

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C

Explanation:

Calculate EkA -kinetic energy of car A

m=1000kg

Va=16.66 m/s

EkA=m*Va²/2

Eka=(1000kg*277.556m²/s²)/2

Eka=138 777.8 J

Calculate kinetic energy of CarB:

m=2000 kg

Vb=8.33 m/s

Ekb=(m*Vb²)/2

Ekb=(2000kg*69.39m²/s²)/2

Ekb=69 388.9 J

compare Eka with EkB

Eka/Ekb=138 777.8 J/69 388.9

Eka/Ekb=2

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