A Car is pushing against the road to go forward with a constant speed speed and direction. It is not acceleration. The road pushes the car forward with a force of 50 newtons. Air Friction resists the car's forward motion with a force of -20 N. How much friction does the road exert on the car?

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?