Question

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

Explanation:

Step1: Convert mass to kg

Given 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 \(v = 39\text{ m/s}\) and \(m = 0.15\text{ kg}\).
Substitute values: \(K.E.=\frac{1}{2}\times0.15\times(39)^{2}\).
First calculate \((39)^{2}=1521\).
Then \(\frac{1}{2}\times0.15\times1521 = 0.075\times1521\).
\(0.075\times1521 = 114.075\approx1.14\times 10^{2}\text{ J}\).

Answer:

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