Answer: The speed of the 15g tennis ball would be approximately 21.9 meters per second if it has 50J of kinetic energy.
Explanation: 1. Convert the mass of the tennis ball from grams to kilograms by dividing by 1000: 15g ÷ 1000 = 0.015 kg
2. Use the formula for kinetic energy: KE = 0.5 x m x v^2, where KE is kinetic energy, m is mass, and v is velocity.
3. Rearrange the formula to solve for velocity: v = √(2KE/m)
4. Substitute the given values: v = √(2 x 50J / 0.015 kg)
5. Simplify the equation: v = √(6666.67) ≈ 81.65 m/s
6. Round the answer to one significant figure: v ≈ 21.9 m/s
Therefore, the speed of the 15g tennis ball would be approximately 21.9 meters per second if it has 50J of kinetic energy.