A ladder 9 m long rest at an angle of 60" to the horizontal against a smooth vertical
wall. Calculate the frictional force and the
normal force of the ground if the ladder
has a mass of 25 kg and its center of
gravity is one-third way up from the
bottom of the ladder. Use g = 9.8ms-2

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.