Does food have energy?

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.

Ln finding the density of liquid why is the method of using a density bottle more accurate than the one of using a measuring cylinder

Olympic skier tina maze skis down a steep slope that descends at an angle of 30∘ below the horizontal. the coefficient of sliding friction between her skis and the snow is 0.10. i found maze's acceleration which is 4.1 m/s^2. but how do you determine maze's speed 4.0 s after starting?