mass (m) = 8kg
velocity (v) = 3 m/s²
Ke = ½mv²
ke = ½ mv²
½ × 8 × 3²
½ × 24²
12
Answer: The right answer is c.
Explanation:
The kinetic energy is defined as follows:
K = 1/2 mv²
If both cars are identical, this means that they have the same mass.
Also, we are told that the speed is also the same for both cars.
If they are going in opposite directions, their velocities have the same magnitude, but opposite signs.
But even though they have different signs, the square (which is the parameter relevant for kinetic energy calculations), is always positive, as any number, elevated to an even power, is positive.
So, we conclude that both cars have the same kinetic energy, in magnitude and in sign.
<u>To find the mass, with only the weight</u>:
⇒ must consider the relationship between the mass and weight
⇒ (<em>in other words</em>) we must find the equation that has both the
mass and weight
<u>Based on our physics knowledge, we know</u>:

- Weight: 147N
- Gravitational Acceleration: 9.8 m/s²
<u>Now let's plug in the values, and solve</u>:

<u>Answer: 15 kg</u>
Hope that helps!
<em>*as a note, if you use the gravitational acceleration as 10m/s², then the answer would be 14.7 kg</em>