Mary and debra stand on a snow-covered roof. they both throw snowballs with the same initial speed, but in different directions. mary throws her snowball downward, at 30° below the horizontal; debra throws her snowball upward, at 30° above the horizontal. which of the following statements are true about just before the snowballs reach the ground below? (there could be more than one correct choice.)

a. mary's snowball has a greater downward acceleration than debra's snowball.
b. debra's snowball has exactly the same acceleration as mary's snowball.
c. debra's snowball will stay in the air longer than mary's snowball.
d. mary's snowball will stay in the air longer than debra's snowball.
e. both snowballs will take the same amount of time to hit the ground.

What is the magnitude of the acceleration vector which causes a particle to move from velocity −5i−2j m/s to −6i+ 7j m/s in 8 seconds. answer in m/s.

While studying chemical reactions and conservation of matter, sarah's class conducted a variety of experiments. sarah and her lab partner found the mass of a wax candle and placed the candle in a flask. the students lit the candle and let it burn to completion. all that was left was wax and charred candle wick. per their teacher's instructions, the students found the mass of the products. their data can be seen in the data table. formulate a hypothesis the students could test to explain why the experiment did not support the law of conservation of matter. a) the students could repeat the experiment using different candles; there might have been a flaw in the candle. b) the experiment should be repeatable. the students should run several trials and then take an average of the after mass in each trial. c) the students should have someone in the class check their measurement skills as they repeat the experiment. they may have made an error using the balance. d) the students should burn the candle in a container that has some type of lid so that any gas that is a product of the reaction can be contained and massed. submit

The rocket is fired vertically and tracked by the radar station shown. when θ reaches 66°, other corresponding measurements give the values r = 32700 ft, r¨ = 85 ft/sec2, and θ˙ = 0.019 rad/sec. calculate the magnitudes of the velocity and acceleration of the rocket at this position.