Question

a yellow ball with a mass of 2 kg is rolling across the floor at 3 m/s. a red ball with a mass of 3 kg is rolling across the same floor at 3 m/s. which ball has greater kinetic energy, and why?

the yellow ball has greater kinetic energy, because it is rolling at a higher position above the ground.

the red ball has greater kinetic energy, because it has a greater mass.

the yellow ball has greater kinetic energy, because it is rolling at a greater speed.

the red ball has greater kinetic energy, because it is releasing more thermal energy.

Explanation:

To determine which ball has greater kinetic energy, we use the kinetic energy formula \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is velocity. Both balls have the same velocity (\( 3 \, \text{m/s} \)). The yellow ball has a mass of \( 2 \, \text{kg} \), and the red ball has a mass of \( 3 \, \text{kg} \). Since kinetic energy is directly proportional to mass when velocity is constant, the ball with the greater mass (red ball) will have greater kinetic energy.

• The first option is incorrect because kinetic energy depends on mass and velocity, not height (height relates to potential energy).
• The third option is incorrect because both balls have the same speed.
• The fourth option is incorrect because thermal energy release is not related to kinetic energy calculation here.

Answer:

B. The red ball has greater kinetic energy, because it has a greater mass.