1. Allison is walking along the beach and sees a sand castle. She wants to place something on top of the sand castle, but she is worried about putting too much force on it. If she puts too much force on the sand castle, it will break. It takes 5000 N to smash the sand castle. The pressure of the items she places on the sand castle is 1200 Pa and the area of the sand castle is 2m * 3m . Does Allison break the sand castle? Explain why based on your calculations. 2. Pisces V is a three-person submersible that can operate at and dive to depths of 1981 meters. What is the pressure (in pascals) on Pisces V at its greatest depth?

3. A statue of a great baseball player weighs 2400 N and has a base that is 4m * 2m . What is the pressure the statue exerts on the floor?

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.