Label the force in each picture as a push or pull. Then describe whether the force is causing a change in speed or direction or both.

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.

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)

Arod made of cobalt with a mass of 0.80 kg is heated to 800°c, then dropped into 6.00 kg of water at 10°c. what is the total change in entropy (in j/k) of the rod-water system, assuming no energy is lost by heat from this system to the surroundings