A moving body of mass $0.5 k g$ has $40 J$ Of kinetic energy. Calculate the speed of the body.

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Solution

Step 1: Given;
Mass, m = $0.5$ kg.
Kinetic energy = $40$ J.
Find; Speed of the body = v.
Step 2: Formula used,
$Kinetic energy = \frac{1}{2} \times mass \times {velocity}^{2}$
$K . E = \frac{1}{2} \times m \times v^{2} .$
Step 3: Calculation,
$K. E space equals space 1 half space cross times space m space cross times space v squared.$
$40 space J space equals 1 half cross times 0.5 space k g cross times v squared$
$v squared equals fraction numerator 40 space J cross times 2 over denominator 0.5 space k g end fraction equals fraction numerator 400 cross times 2 over denominator 5 end fraction open parentheses m over s close parentheses squared$
$v equals square root of 800 over 5 end root m s to the power of negative 1 end exponent$
$v equals square root of 160 m s to the power of negative 1 end exponent$
$v equals 4 square root of 10 m s to the power of negative 1 end exponent$
Hence, speed of the object is $4 \sqrt{10} m s^{- 1}$ .

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