Two watermelons fall off a kitchen counter. The masses and speeds of the fruits are in the table

Question

Watermelon A mass 4 speed 2
Watermelon B mass 4 speed 4
How do the kinetic and or potential energies of the fruit compare
Both fruits have the same kinetic and potential energy
Watermelon A has more kinetic energy
Both fruits have only potential energy and no kinetic energy
Watermelon B has more kinetic energy

Answer 1

To compare the kinetic energies of the two watermelons, we can use the formula for kinetic energy:

\[ KE = \frac{1}{2} mv^2 \]

where \( m \) is the mass and \( v \) is the speed.

1. Watermelon A:

   • Mass (\( m_A \)) = 4 kg
   • Speed (\( v_A \)) = 2 m/s
   • Kinetic Energy (\( KE_A \)): \[ KE_A = \frac{1}{2} \times 4 \times (2^2) = \frac{1}{2} \times 4 \times 4 = 8 \text{ J} \]

2. Watermelon B:

   • Mass (\( m_B \)) = 4 kg
   • Speed (\( v_B \)) = 4 m/s
   • Kinetic Energy (\( KE_B \)): \[ KE_B = \frac{1}{2} \times 4 \times (4^2) = \frac{1}{2} \times 4 \times 16 = 32 \text{ J} \]

Now, we can compare the kinetic energies:

• \( KE_A = 8 \text{ J} \)
• \( KE_B = 32 \text{ J} \)

Since \( KE_B > KE_A \), we conclude that Watermelon B has more kinetic energy.

Regarding potential energy, since we do not have any information on their heights or positions, we cannot assume that both fruits have only potential energy or compare potential energies directly. However, if they are falling, their potential energy is decreasing as they fall.

Thus, the correct summary is: Watermelon B has more kinetic energy.