Question1

A diffraction grating has 3816 lines/cm. Light that contains all wavelengths between 464 and 636 nm shines on the grating. Compute the width of dark area between first and second order spectra on a screen 3.3 m away.

Question2

To give a 20 kg child a ride, two teenagers pull on a 4.0 kg sled with ropes. Both teenagers pull with a force of 55 N at an angle of 35 relative to the forward direction that is the direction of motion. In adding, the snow exerts a retarding force on the sled that points opposite to the direction of motion, and has a magnitude of 57 N. Find out the acceleration of the sled and child.