A block of mass 0.5 kg is pushed against a horizontal spring until the spring is compressed a distance x = 0.4 m. The spring constant is 450 N/m. When it is released the block travels along a horizontal frictionless surface then reaches a vertical circular track of radius R = 2.9 m and continues to move up the track. The block experiences friction while sliding up the track. The block reaches the top of the track with a speed of 4.1 m/s. Find the change in mechanical energy caused by friction (in J).

Explain vector addition, triangle method and parallelogram method

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?

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.