k = 1/2 × m × v^2
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1. k = 1/2 × 60 × ( 10 )^2
k = 30 × 100
k = 3000 j
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2. k = 1/2 × 60 × ( 9 )^2
k = 30 × 81
k = 2430 j
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3. k = 1/2 × 60 × ( 4 )^2
k = 30 × 16
k = 480 j
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4. k = 1/2 × 60 × ( 6 )^2
k = 30 × 36
k = 1080 j
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5. k = 1/2 × 60 × ( 0 ) ^2
k = 30 × 0
k = 0 j