| 1. | matter | 2. | energy | 
| 3. | energy and matter | 4. | energy, matter, and momentum | 
| 1. | Mechanical transverse waves can propagate through all mediums. | 
| 2. | Longitudinal waves can propagate through solids only. | 
| 3. | Mechanical transverse waves can propagate through solids only. | 
| 4. | Longitudinal waves can propagate through vacuum. | 
| 1. | \(y=0.6 \sin 2 \pi\left(t+\dfrac{x}{2}\right)\) | 2. | \(y=-0.4 \sin 2 \pi\left(t+\dfrac{x}{2}\right) \) | 
| 3. | \(y=0.4 \sin 2 \pi\left(t+\dfrac{x}{2}\right) \) | 4. | \(y=-0.4 \sin 2 \pi\left(t-\dfrac{x}{2}\right)\) | 
| 1. | \(1\) second | 
| 2. | \(0.5\) second | 
| 3. | \(2\) seconds | 
| 4. | The data given is insufficient | 
| 1. |  | 2. |  | 
| 3. |  | 4. |  |