Athin uniform film of refractive index 1.750 is placed on a sheet of glass with a refractive index 1.50. at room temperature ( 22.2 ∘c), this film is just thick enough for light with a wavelength 583.5 nm reflected off the top of the film to be canceled by light reflected from the top of the glass. after the glass is placed in an oven and slowly heated to 174 ∘c, you find that the film cancels reflected light with a wavelength 587.5 nm .

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?