Question

A body of mass 10 kg moving at a height of 2 m, with uniform speed of 2 m/s. Its total energy is

• A. 316 J
• B. 216 J
• C. 116 J
• D. 392 J

Answer 1

Answer: (B)

216 J

Answer 2

The total energy of a body is the sum of its kinetic energy and potential energy. The formula for total mechanical energy ($E$) is given by:

$E = KE + PE$

where $KE$ is the kinetic energy and $PE$ is the potential energy.

1. Calculate Kinetic Energy (KE):

   The formula for kinetic energy is $KE = \frac{1}{2}mv^2$, where $m$ is the mass and $v$ is the speed. Given: Mass ($m$) = 10 kg Speed ($v$) = 2 m/s

   $KE = \frac{1}{2} \times 10 \text{ kg} \times (2 \text{ m/s})^2$ $KE = \frac{1}{2} \times 10 \times 4$ $KE = 5 \times 4$ $KE = 20 \text{ J}$

2. Calculate Potential Energy (PE):

   The formula for potential energy is $PE = mgh$, where $m$ is the mass, $g$ is the acceleration due to gravity, and $h$ is the height. Given: Mass ($m$) = 10 kg Height ($h$) = 2 m Acceleration due to gravity ($g$) = 9.8 m/s² (standard value, assumed as not specified)

   $PE = 10 \text{ kg} \times 9.8 \text{ m/s}^2 \times 2 \text{ m}$ $PE = 196 \text{ J}$

3. Calculate Total Energy (E):

   $E = KE + PE$ $E = 20 \text{ J} + 196 \text{ J}$ $E = 216 \text{ J}$

The calculated total energy is 216 J.