Final answer:
The statement about the Izod and Charpy impact tests' orientation is true. The claim that a rock's kinetic energy increases with height is false; its potential energy increases instead. The mass of a pendulum's bob does not affect its motion if the pendula are of the same length and displaced by the same angle.
Step-by-step explanation:
The statement regarding pendulum tests for checking the toughness of a material refers to impact strength tests, specifically the Izod and Charpy tests. As the student indicated, the major difference between these two tests is the orientation of the test piece during the impact. The Izod test has the piece held vertically while the Charpy test has the piece held horizontally. This is true.
In regards to the principles of physics, when a rock is thrown into the air, as it rises, its kinetic energy is converted to potential energy, and not the other way around. Thus, as it falls to the ground, the potential energy is converted back into kinetic energy due to gravity. Therefore, the correct answer is false; the increase in height increases the rock's potential energy, and as it falls, the potential energy is converted into kinetic energy, which increases with velocity.
When discussing pendulums, the motion of simple pendulums depends on the length and the acceleration due to gravity, and is not affected by the mass of the bob. Therefore, regardless of whether one bob is 10 kg and the other is 100 kg, if they are both displaced by the same angle, their motion will not differ.