3 Physics questions 1. A steam shovel raises 450.0 kg of dirt a vertical distance of 8.6 m. The engine provides 200KJ of energy as heat for the steam shovel to lift the dirt. How much work, in Joules, is done by the steam shovel? Use g as 9.81m/s2.WRITE YOUR ANSWER IN SCIENTIFIC NOTATION

2. A coal-burning power plant has an efficiency of 35 percent. If the power plant uses 737M J of energy as heat, how much work is done by the power plant?

3. A certain diesel engine performs 372 J of work in each cycle with an efficiency of 33.0 percent. How much energy is transferred from the engine to the exhaust and cooling system as heat?

The earth exerts a gravitational force of 500 n on amy. what is amy’s mass in kg?

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.

Abird flies directly overhead from where you stand at an altitude of 300.0 m and at a speed horizontal to the ground of 20.0 m/s. the bird has a mass of 2.0 kg. the radius vector to the bird makes an angle \thetaθ with respect to the ground. the radius vector to the bird and its momentum vector lie in the xyxy-plane. what is the bird’s angular momentum about the point where you are standing?