Question

an object of mass 1.50 x 10² g is accelerated to a speed of 39 ms⁻¹. what is the kinetic energy of this object in joules? 2.73 x 10³ j 5.83 x 10³ j 1.32 x 10² j 2.45 x 10⁵ j 1.14 x 10² j

Explanation:

Step1: Convert mass to kg

The mass \(m = 1.50\times10^{2}\text{ g}\). Since \(1\text{ kg}=1000\text{ g}\), then \(m=\frac{1.50\times 10^{2}}{1000}\text{ kg}=0.15\text{ kg}\).

Step2: Use kinetic energy formula

The formula for kinetic energy is \(K.E.=\frac{1}{2}mv^{2}\), where \(m\) is mass and \(v\) is velocity. Given \(v = 39\text{ m/s}\) and \(m=0.15\text{ kg}\).
Substitute values: \(K.E.=\frac{1}{2}\times0.15\times(39)^{2}\).
First calculate \((39)^{2}=1521\).
Then \(\frac{1}{2}\times0.15\times1521 = 0.075\times1521=114.075\approx1.14\times 10^{2}\text{ J}\).

Answer:

\(1.14\times 10^{2}\text{ J}\)