You and your friend are the rock toy competition your friend takes 8kg rock'n'roll it at the speed of three m/s you take a 3 kg rock and throw it at the speed 9 m/s which of the following has more kinetic energy anyway

Answer 1

To determine which object has more kinetic energy, we can use the kinetic energy formula:

\[ KE = \frac{1}{2} m v^2 \]

where \(m\) is the mass of the object and \(v\) is its velocity.

For your friend's rock:

• Mass (\(m\)) = 8 kg
• Velocity (\(v\)) = 3 m/s

Calculating the kinetic energy for the friend's rock:

\[ KE_{friend} = \frac{1}{2} \times 8 , \text{kg} \times (3 , \text{m/s})^2 \] \[ KE_{friend} = \frac{1}{2} \times 8 \times 9 = \frac{1}{2} \times 72 = 36 , \text{Joules} \]

For your rock:

• Mass (\(m\)) = 3 kg
• Velocity (\(v\)) = 9 m/s

Calculating the kinetic energy for your rock:

\[ KE_{you} = \frac{1}{2} \times 3 , \text{kg} \times (9 , \text{m/s})^2 \] \[ KE_{you} = \frac{1}{2} \times 3 \times 81 = \frac{1}{2} \times 243 = 121.5 , \text{Joules} \]

Comparison:

• Kinetic energy of your friend's rock: 36 Joules
• Kinetic energy of your rock: 121.5 Joules

Your rock has more kinetic energy.