Correct option is A
The correct answer is (a) 5.625 J
Explanation
• Kinetic energy is the energy possessed by an object due to its motion, and its SI unit is the joule (J).
• The mathematical expression for kinetic energy is:
Kinetic Energy = 1/2 × m × v²,
where m is the mass of the object and v is its velocity.
• Before calculation, the mass must be converted into the standard SI unit (kilograms):
50 g = 50 ÷ 1000 kg = 0.05 kg.
• Substituting the given values into the formula:
Kinetic Energy = 1/2 × 0.05 × (15)²
= 0.025 × 225.
• The final calculation gives:
Kinetic Energy = 5.625 joule.
• This confirms the amount of energy possessed by the ball.
Information Booster:
• Kinetic energy is a scalar quantity and is always positive as long as the object is in motion, because mass is positive and velocity is squared.
• According to the work–energy theorem, the work done on an object by a net force is equal to the change in its kinetic energy.
Additional Knowledge (Incorrect options):
• 3.750 J (Option b):
This value is mathematically incorrect and does not satisfy the kinetic energy formula for the given mass and velocity. It is a distractor with no valid calculation basis.
• 1.875 J (Option c):
This value is exactly one-third of the correct answer and is incorrect. Using this value violates the laws of classical mechanics for a 50 g object moving at 15 m/s.
• 7.500 J (Option d):
This value is incorrect and does not match the product of 1/2 × m × v² for the given data. It could result from using an incorrect mass of about 66.7 g instead of 50 g.
