What happens to the kinetic energy of a moving object if its velocity is tripled?
Show answer & explanation
Correct answer: B
Explanation
Correct Answer
It becomes nine times greater.
Explanation
The kinetic energy of a moving object is directly proportional to the square of its velocity. The standard formula to calculate kinetic energy is:
Kinetic Energy = (1/2) mv2
In this formula, mass represents the weight-related property of the object and velocity represents its speed in a given direction.
If the velocity of the object is tripled, the new velocity becomes 3 times the original velocity. When you plug this into the formula, the velocity term is squared, which means you have to square the number 3. Since 3 multiplied by 3 equals 9, the new calculation reveals that the kinetic energy increases by a factor of 9. Therefore, because kinetic energy depends on the square of the speed, tripling the velocity makes the total kinetic energy nine times greater than it was originally.
Key Points
Kinetic energy is a scalar quantity, meaning it possesses only magnitude and no specific direction.
The standard International System of Units (SI) unit used for measuring kinetic energy is the Joule (J).
If the velocity of an object is doubled, its kinetic energy increases by four times because 2 squared is 4. Similarly, if the velocity is halved, the kinetic energy drops to one-fourth of its original value.
Mass and kinetic energy share a linear relationship, meaning if the mass of the object is doubled while keeping velocity constant, the kinetic energy will simply double.
Additional Facts
Kinetic energy can never be a negative value because mass is always positive and the square of velocity is always a positive number.
The Work-Energy Theorem states that the net work done on an object by external forces is equal to the change in its kinetic energy.
Important Questions and Answers
Question: What will happen to the kinetic energy of an object if its mass is doubled and its velocity is doubled at the same time?
Answer: The kinetic energy will increase eightfold. This happens because doubling the mass multiplies the energy by 2, and doubling the velocity multiplies the energy by 4 (since 2 squared is 4). Multiplying 2 by 4 gives an 8-times increase.
Question: How does the kinetic energy of a heavy truck compare to a small car traveling at the exact same velocity?
Answer: The heavy truck will have much greater kinetic energy because it has a larger mass, and kinetic energy is directly proportional to the mass of the object.