During a lab activity in class, you are trying to collect data on a marble to determine its launch (initial) velocity. You decide to launch the marble at 90 degrees (vertically
straight up) and measure the maximum height of the marble. After several trials of
data, you determine the average maximum height to be 4.2 m above the initial height
of the marble. Based on your measurements, what is the launch (initial) velocity of the
marble?
Assume acceleration due to gravity is -9.81 m/s2. Answer in units of meters/second.

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.

Atomic nuclei of almost all elements consist of

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration