A Level Physics Practice Exam

How is kinetic energy (KE) calculated for an object with mass m and velocity v?

1. KE = mv

2. KE = 2mv

3. KE = 1/2 mv^2

4. KE = mv^2

The correct answer is: KE = 1/2 mv^2

Kinetic energy (KE) is defined as the energy possessed by an object due to its motion. The formula to calculate kinetic energy takes into account both the mass of the object and its velocity. The correct expression for kinetic energy is derived from the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy. For an object with mass \( m \) and moving at a velocity \( v \), the kinetic energy is calculated using the formula: \[ KE = \frac{1}{2} mv^2. \] This equation components can be understood as follows: - The factor of \( \frac{1}{2} \) arises from the process of integrating the force applied to move the object. - The term \( mv^2 \) indicates that kinetic energy depends on the square of the velocity, meaning that if the velocity of the object doubles, its kinetic energy will increase by a factor of four. This squared relationship shows that velocity has a more significant impact on kinetic energy than mass alone. This understanding also highlights why the other options do not accurately represent kinetic energy. The other choices, such as \( mv \), \( 2mv \), and \( mv^2