Determined to test gravity, a student walks off the Burj Khalifa (aka really tall building) in Dubai, which is
829 m high, and falls freely. His initial velocity is zero. Jetpack Woman leaves the roof 5 s later to save
the student with an initial velocity downward and then is in free-fall. In order both to catch the student
and to prevent injury to her, Jetpack Woman should catch the student at a sufficiently great height and
arrive at the ground with zero velocity. The upward acceleration that accomplishes this is provided by
Jetpack Woman's jet pack, which she turns on just as she catches the student; before then the student is
in free-fall. To prevent discomfort to the student, the magnitude of the acceleration is limited to four
times gravity (4 G). (You may assume that Jetpack Woman has superpowers, which allow her to change
velocity instantaneously.) How high above the ground must Jetpack Woman catch the student?
Answers: 2
Physics, 22.06.2019 12:00, P4thing
Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?
Answers: 3
Physics, 22.06.2019 13:00, chie42
Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.
Answers: 2
Determined to test gravity, a student walks off the Burj Khalifa (aka really tall building) in Dubai...
Mathematics, 06.10.2019 10:40
Social Studies, 06.10.2019 10:40