a horse starts from rest and speeds up with constant acceleration. if it has gone a distance of 100m at the point when it reaches a speed of 12m/s, what is its acceleration? (Apex question btw)

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?