When a plate is dropped, it initially has gravitational potential energy due to its height. As it falls, this energy is converted into kinetic energy. Upon impact with the ground, the kinetic energy is transformed into other forms. The collision produces sound waves (sound energy) and causes vibrations that generate heat through friction (heat energy). Therefore, the potential energy is primarily converted into both sound and heat energy.

Final answer: potential energy is converted into sound energy and heat energy.