Calculating the girl's kinetic energy before hitting the water.

To determine the kinetic energy of the girl right before she hits the water, we can use the principle of conservation of energy. Initially, all of her energy is in the form of gravitational potential energy (PE), which is converted into kinetic energy (KE) as she falls. The potential energy at the height of 5 meters can be calculated using the formula: \[ PE = mgh \] where: - \( m \) is the mass of the girl (50 kg) - \( g \) is the acceleration due to gravity (\( 9.8 \, \text{m/s}^2 \)) - \( h \) is the height from which she jumps (5 meters) Now, calculating the potential energy: \[ PE = (50 \, \text{kg}) \cdot (9.8 \, \text{m/s}^2) \cdot (5 \, \text{m}) \] \[ PE = 2450 \, \text{Joules} \] Since all the potential energy converts into kinetic energy right before she hits the water, the kinetic energy is also 2450 Joules. So, the correct answer is: a. 2450 J